add upstream 10.21

138 files changed, 2109 insertions, 1802 deletions

diff --git a/Bugs.txt b/Bugs.txt
index fe61dc97..9d0592c8 100755
--- a/Bugs.txt
+++ b/Bugs.txt
@@ -5,27 +5,25 @@ the ones mentioned below. The remaining issues that are yet to be fixed are list
 
 
 -----------------
-| libcurl 7.6.7 |
+| libcurl 7.6.9 |
 -----------------
 __________________________________________________________________________________________________________
 /lib/ftp.c
 https://github.com/curl/curl/issues/1455
 
-Add:
-	static bool is_routable_ip_v4(unsigned int ip[4])
-	{
-		if (ip[0] == 127 || //127.0.0.0/8 (localhost)
-			ip[0] == 10  || //10.0.0.0/8 (private)
-			(ip[0] == 192 && ip[1] == 168) ||  //192.168.0.0/16 (private)
-			(ip[0] == 169 && ip[1] == 254) ||  //169.254.0.0/16 (link-local)
-			(ip[0] == 172 && ip[1] / 16 == 1)) //172.16.0.0/12 (private)
-			return false;
-		return true;
-	}
++	static bool is_routable_ip_v4(unsigned int ip[4])
++	{
++		if (ip[0] == 127 || //127.0.0.0/8 (localhost)
++			ip[0] == 10  || //10.0.0.0/8 (private)
++			(ip[0] == 192 && ip[1] == 168) ||  //192.168.0.0/16 (private)
++			(ip[0] == 169 && ip[1] == 254) ||  //169.254.0.0/16 (link-local)
++			(ip[0] == 172 && ip[1] / 16 == 1)) //172.16.0.0/12 (private)
++			return false;
++		return true;
++	}
 
 
 - if (data->set.ftp_skip_ip)
-
 +	bool skipIp = data->set.ftp_skip_ip;
 +	if (!skipIp && !is_routable_ip_v4(ip))
 +	{
diff --git a/Changelog.txt b/Changelog.txt
index a4103889..cc6a1c8a 100755
--- a/Changelog.txt
+++ b/Changelog.txt
@@ -1,9 +1,27 @@
+FreeFileSync 10.21 [2020-03-17]
+-------------------------------
+Preselect last-used email address
+Select log file format (HTML or plain text)
+Aggregate email notifications when hitting sending limits
+Show code literals in system error messages
+Limit conflict item count for log file warning message
+Show log icon error indicator even if error occured after sync
+Disable background drag & drop when showing modal dialog
+Hide dummy model, vendor names in log files
+Fixed ANSI encoding used for log file time formatting
+Reduced memory consumption for large number of log messages
+Correctly parse lock files despite corrupted trail data
+Show emoji instead of Unicode icon in email subject
+Fixed IWbemServices::ConnectServer error after sync
+Fixed aggregate email logs incomplete truncation
+
+
 FreeFileSync 10.20 [2020-02-14]
 -------------------------------
-Send email notifications after sync
+Send email notifications after sync (Donation Edition)
 Generate log files in HTML format
 Detect sync database consistency errors
-Start log file with preview of first 50 errors/warnings
+Start log file with preview of first 25 errors/warnings
 Mitigate lock file data corruption
 Print Windows error codes in hexadecimal
 Fixed missing MTP and network links in folder picker (Linux)
diff --git a/FreeFileSync/Build/Resources/Icons.zip b/FreeFileSync/Build/Resources/Icons.zip
index 79a4dd7f..0a393bbc 100644
--- a/FreeFileSync/Build/Resources/Icons.zip
+++ b/FreeFileSync/Build/Resources/Icons.zip
diff --git a/FreeFileSync/Build/Resources/Languages.zip b/FreeFileSync/Build/Resources/Languages.zip
index 81e8e960..3f00d604 100644
--- a/FreeFileSync/Build/Resources/Languages.zip
+++ b/FreeFileSync/Build/Resources/Languages.zip
diff --git a/FreeFileSync/Source/Makefile b/FreeFileSync/Source/Makefile
index 87352ea4..5d4f6b20 100644..100755
--- a/FreeFileSync/Source/Makefile
+++ b/FreeFileSync/Source/Makefile
@@ -28,24 +28,25 @@ LINKFLAGS += `pkg-config --libs libselinux`
 endif
 
 CPP_FILES=
+CPP_FILES+=application.cpp
+CPP_FILES+=base_tools.cpp
+CPP_FILES+=config.cpp
+CPP_FILES+=ffs_paths.cpp
+CPP_FILES+=icon_buffer.cpp
+CPP_FILES+=localization.cpp
+CPP_FILES+=log_file.cpp
+CPP_FILES+=perf_check.cpp
+CPP_FILES+=status_handler.cpp
 CPP_FILES+=base/algorithm.cpp
-CPP_FILES+=base/application.cpp
 CPP_FILES+=base/binary.cpp
 CPP_FILES+=base/comparison.cpp
-CPP_FILES+=base/config.cpp
 CPP_FILES+=base/db_file.cpp
 CPP_FILES+=base/dir_lock.cpp
-CPP_FILES+=base/ffs_paths.cpp
 CPP_FILES+=base/file_hierarchy.cpp
-CPP_FILES+=base/icon_buffer.cpp
 CPP_FILES+=base/icon_loader.cpp
-CPP_FILES+=base/localization.cpp
-CPP_FILES+=base/log_file.cpp
 CPP_FILES+=base/parallel_scan.cpp
 CPP_FILES+=base/path_filter.cpp
-CPP_FILES+=base/perf_check.cpp
 CPP_FILES+=base/resolve_path.cpp
-CPP_FILES+=base/status_handler.cpp
 CPP_FILES+=base/structures.cpp
 CPP_FILES+=base/synchronization.cpp
 CPP_FILES+=base/versioning.cpp
@@ -90,6 +91,7 @@ CPP_FILES+=../../zen/legacy_compiler.cpp
 CPP_FILES+=../../zen/open_ssl.cpp
 CPP_FILES+=../../zen/process_priority.cpp
 CPP_FILES+=../../zen/shutdown.cpp
+CPP_FILES+=../../zen/sys_error.cpp
 CPP_FILES+=../../zen/system.cpp
 CPP_FILES+=../../zen/thread.cpp
 CPP_FILES+=../../zen/zlib_wrap.cpp
diff --git a/FreeFileSync/Source/RealTimeSync/Makefile b/FreeFileSync/Source/RealTimeSync/Makefile
index 3d0e98ec..9c7f88e0 100755
--- a/FreeFileSync/Source/RealTimeSync/Makefile
+++ b/FreeFileSync/Source/RealTimeSync/Makefile
@@ -20,11 +20,11 @@ CPP_FILES+=tray_menu.cpp
 CPP_FILES+=monitor.cpp
 CPP_FILES+=folder_selector2.cpp
 CPP_FILES+=../afs/abstract.cpp
-CPP_FILES+=../base/icon_buffer.cpp
 CPP_FILES+=../base/icon_loader.cpp
-CPP_FILES+=../base/localization.cpp
 CPP_FILES+=../base/resolve_path.cpp
-CPP_FILES+=../base/ffs_paths.cpp
+CPP_FILES+=../ffs_paths.cpp
+CPP_FILES+=../icon_buffer.cpp
+CPP_FILES+=../localization.cpp
 CPP_FILES+=../../../zen/dir_watcher.cpp
 CPP_FILES+=../../../zen/file_access.cpp
 CPP_FILES+=../../../zen/file_io.cpp
@@ -32,6 +32,7 @@ CPP_FILES+=../../../zen/file_traverser.cpp
 CPP_FILES+=../../../zen/format_unit.cpp
 CPP_FILES+=../../../zen/legacy_compiler.cpp
 CPP_FILES+=../../../zen/shutdown.cpp
+CPP_FILES+=../../../zen/sys_error.cpp
 CPP_FILES+=../../../zen/thread.cpp
 CPP_FILES+=../../../zen/zstring.cpp
 CPP_FILES+=../../../wx+/file_drop.cpp
diff --git a/FreeFileSync/Source/RealTimeSync/application.cpp b/FreeFileSync/Source/RealTimeSync/application.cpp
index 7f81883b..037d7059 100644
--- a/FreeFileSync/Source/RealTimeSync/application.cpp
+++ b/FreeFileSync/Source/RealTimeSync/application.cpp
@@ -15,12 +15,12 @@
 #include <wx+/popup_dlg.h>
 #include <wx+/image_resources.h>
 #include "config.h"
-#include "../base/localization.h"
-#include "../base/ffs_paths.h"
-#include "../base/return_codes.h"
-#include "../base/fatal_error.h"
-#include "../base/help_provider.h"
 #include "../base/resolve_path.h"
+#include "../localization.h"
+#include "../ffs_paths.h"
+#include "../return_codes.h"
+#include "../fatal_error.h"
+#include "../help_provider.h"
 
     #include <gtk/gtk.h>
 
@@ -61,13 +61,15 @@ bool Application::OnInit()
                                           (fff::getResourceDirPf() + "Gtk3Styles.css").c_str(), //const gchar* path,
                                           &error); //GError** error
         if (error)
-            throw SysError(formatSystemError(L"gtk_css_provider_load_from_data", replaceCpy(_("Error Code %x"), L"%x", numberTo<std::wstring>(error->code)), utfTo<std::wstring>(error->message)));
+            throw SysError(formatSystemError(L"gtk_css_provider_load_from_data", replaceCpy(_("Error Code %x"), L"%x",
+                                                                                            numberTo<std::wstring>(error->code)),
+                                             utfTo<std::wstring>(error->message)));
 
         ::gtk_style_context_add_provider_for_screen(::gdk_screen_get_default(),               //GdkScreen* screen,
                                                     GTK_STYLE_PROVIDER(provider),             //GtkStyleProvider* provider,
                                                     GTK_STYLE_PROVIDER_PRIORITY_APPLICATION); //guint priority
     }
-    catch (const SysError& e) { std::cerr << utfTo<std::string>(e.toString()) << "\n"; }
+    catch (const SysError& e) { std::cerr << utfTo<std::string>(e.toString()) << '\n'; }
 #else
 #error unknown GTK version!
 #endif
@@ -158,7 +160,7 @@ int Application::OnRun()
         fff::logFatalError(e.what()); //it's not always possible to display a message box, e.g. corrupted stack, however low-level file output works!
 
         const auto titleFmt = copyStringTo<std::wstring>(wxTheApp->GetAppDisplayName()) + SPACED_DASH + _("An exception occurred");
-        std::cerr << utfTo<std::string>(titleFmt + SPACED_DASH) << e.what() << "\n";
+        std::cerr << utfTo<std::string>(titleFmt + SPACED_DASH) << e.what() << '\n';
         return fff::FFS_RC_EXCEPTION;
     }
     //catch (...) -> let it crash and create mini dump!!!
diff --git a/FreeFileSync/Source/RealTimeSync/config.cpp b/FreeFileSync/Source/RealTimeSync/config.cpp
index 3f084f3a..7051c6d1 100644
--- a/FreeFileSync/Source/RealTimeSync/config.cpp
+++ b/FreeFileSync/Source/RealTimeSync/config.cpp
@@ -8,8 +8,8 @@
 #include <zen/file_access.h>
 #include <zenxml/xml.h>
 #include <wx/intl.h>
-#include "../base/ffs_paths.h"
-#include "../base/localization.h"
+#include "../ffs_paths.h"
+#include "../localization.h"
 
 using namespace zen;
 using namespace rts;
diff --git a/FreeFileSync/Source/RealTimeSync/gui_generated.cpp b/FreeFileSync/Source/RealTimeSync/gui_generated.cpp
index 7709981d..dccc3495 100644
--- a/FreeFileSync/Source/RealTimeSync/gui_generated.cpp
+++ b/FreeFileSync/Source/RealTimeSync/gui_generated.cpp
@@ -121,10 +121,13 @@ MainDlgGenerated::MainDlgGenerated( wxWindow* parent, wxWindowID id, const wxStr
     m_staticText11->Wrap( -1 );
     m_staticText11->SetForegroundColour( wxSystemSettings::GetColour( wxSYS_COLOUR_GRAYTEXT ) );
 
-    bSizer152->Add( m_staticText11, 0, wxALIGN_CENTER_VERTICAL|wxLEFT, 2 );
+    bSizer152->Add( m_staticText11, 0, wxALIGN_CENTER_VERTICAL|wxRIGHT|wxLEFT, 2 );
 
+    m_hyperlink243 = new wxHyperlinkCtrl( this, wxID_ANY, _("Show examples"), wxEmptyString, wxDefaultPosition, wxDefaultSize, wxHL_DEFAULT_STYLE );
+    bSizer152->Add( m_hyperlink243, 0, wxALIGN_CENTER_VERTICAL|wxLEFT, 5 );
 
-    bSizer161->Add( bSizer152, 0, wxALIGN_CENTER_HORIZONTAL|wxBOTTOM|wxRIGHT|wxLEFT, 5 );
+
+    bSizer161->Add( bSizer152, 0, wxALL|wxALIGN_CENTER_HORIZONTAL, 5 );
 
 
     bSizerMain->Add( bSizer161, 0, wxALL|wxEXPAND, 5 );
@@ -303,6 +306,7 @@ MainDlgGenerated::MainDlgGenerated( wxWindow* parent, wxWindowID id, const wxStr
     m_menuFile->Bind(wxEVT_COMMAND_MENU_SELECTED, wxCommandEventHandler( MainDlgGenerated::OnMenuQuit ), this, m_menuItemQuit->GetId());
     m_menuHelp->Bind(wxEVT_COMMAND_MENU_SELECTED, wxCommandEventHandler( MainDlgGenerated::OnShowHelp ), this, m_menuItemContent->GetId());
     m_menuHelp->Bind(wxEVT_COMMAND_MENU_SELECTED, wxCommandEventHandler( MainDlgGenerated::OnMenuAbout ), this, m_menuItemAbout->GetId());
+    m_hyperlink243->Connect( wxEVT_COMMAND_HYPERLINK, wxHyperlinkEventHandler( MainDlgGenerated::OnHelpRealTimeSync ), NULL, this );
     m_bpButtonAddFolder->Connect( wxEVT_COMMAND_BUTTON_CLICKED, wxCommandEventHandler( MainDlgGenerated::OnAddFolder ), NULL, this );
     m_bpButtonRemoveTopFolder->Connect( wxEVT_COMMAND_BUTTON_CLICKED, wxCommandEventHandler( MainDlgGenerated::OnRemoveTopFolder ), NULL, this );
     m_buttonStart->Connect( wxEVT_COMMAND_BUTTON_CLICKED, wxCommandEventHandler( MainDlgGenerated::OnStart ), NULL, this );
diff --git a/FreeFileSync/Source/RealTimeSync/gui_generated.h b/FreeFileSync/Source/RealTimeSync/gui_generated.h
index 1fd190f0..5cc0f0ca 100644
--- a/FreeFileSync/Source/RealTimeSync/gui_generated.h
+++ b/FreeFileSync/Source/RealTimeSync/gui_generated.h
@@ -24,6 +24,7 @@ namespace zen { class BitmapTextButton; }
 #include <wx/stattext.h>
 #include <wx/sizer.h>
 #include <wx/statbmp.h>
+#include <wx/hyperlink.h>
 #include <wx/statline.h>
 #include <wx/bmpbuttn.h>
 #include <wx/button.h>
@@ -64,6 +65,7 @@ protected:
     wxStaticText* m_staticText10;
     wxStaticBitmap* m_bitmapBatch;
     wxStaticText* m_staticText11;
+    wxHyperlinkCtrl* m_hyperlink243;
     wxStaticLine* m_staticline2;
     wxPanel* m_panelMain;
     wxStaticBitmap* m_bitmapFolders;
@@ -95,6 +97,7 @@ protected:
     virtual void OnMenuQuit( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnShowHelp( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnMenuAbout( wxCommandEvent& event ) { event.Skip(); }
+    virtual void OnHelpRealTimeSync( wxHyperlinkEvent& event ) { event.Skip(); }
     virtual void OnAddFolder( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnRemoveTopFolder( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnStart( wxCommandEvent& event ) { event.Skip(); }
diff --git a/FreeFileSync/Source/RealTimeSync/main_dlg.cpp b/FreeFileSync/Source/RealTimeSync/main_dlg.cpp
index 57e188ea..694d6e79 100644
--- a/FreeFileSync/Source/RealTimeSync/main_dlg.cpp
+++ b/FreeFileSync/Source/RealTimeSync/main_dlg.cpp
@@ -17,9 +17,9 @@
 #include "config.h"
 #include "tray_menu.h"
 #include "app_icon.h"
-#include "../base/help_provider.h"
-#include "../base/icon_buffer.h"
-#include "../base/ffs_paths.h"
+#include "../help_provider.h"
+#include "../icon_buffer.h"
+#include "../ffs_paths.h"
 #include "../version/version.h"
 
     #include <gtk/gtk.h>
@@ -177,6 +177,7 @@ void MainDialog::onQueryEndSession()
 }
 
 
+
 void MainDialog::OnShowHelp(wxCommandEvent& event)
 {
     fff::displayHelpEntry(L"realtimesync", this);
@@ -201,7 +202,7 @@ void MainDialog::OnMenuAbout(wxCommandEvent& event)
 #endif
 
     build += SPACED_BULLET;
-    build += formatTime<wxString>(FORMAT_DATE, getCompileTime());
+    build += utfTo<wxString>(formatTime(formatDateTag, getCompileTime()));
 
     showNotificationDialog(this, DialogInfoType::info, PopupDialogCfg().
                            setTitle(_("About")).
diff --git a/FreeFileSync/Source/RealTimeSync/main_dlg.h b/FreeFileSync/Source/RealTimeSync/main_dlg.h
index d20b889c..39052f93 100644
--- a/FreeFileSync/Source/RealTimeSync/main_dlg.h
+++ b/FreeFileSync/Source/RealTimeSync/main_dlg.h
@@ -38,6 +38,7 @@ private:
 
     void OnClose          (wxCloseEvent&  event ) override  { Destroy(); }
     void OnShowHelp       (wxCommandEvent& event) override;
+    void OnHelpRealTimeSync(wxHyperlinkEvent& event) override { OnShowHelp(event); }
     void OnMenuAbout      (wxCommandEvent& event) override;
     void OnAddFolder      (wxCommandEvent& event) override;
     void OnRemoveFolder   (wxCommandEvent& event);
diff --git a/FreeFileSync/Source/RealTimeSync/monitor.cpp b/FreeFileSync/Source/RealTimeSync/monitor.cpp
index d5266c6c..66a83f3c 100644
--- a/FreeFileSync/Source/RealTimeSync/monitor.cpp
+++ b/FreeFileSync/Source/RealTimeSync/monitor.cpp
@@ -26,10 +26,10 @@ std::set<Zstring, LessNativePath> waitForMissingDirs(const std::vector<Zstring>&
                                                      const std::function<void(const Zstring& folderPath)>& requestUiUpdate, std::chrono::milliseconds cbInterval)
 {
     //early failure! check for unsupported folder paths:
-    for (const Zstring& protoName : { Zstr("ftp"), Zstr("sftp"), Zstr("mtp"), Zstr("gdrive") })
+    for (const std::string& protoName : { "ftp", "sftp", "mtp", "gdrive" })
         for (const Zstring& phrase : folderPathPhrases)
             //hopefully clear enough now: https://freefilesync.org/forum/viewtopic.php?t=4302
-            if (startsWithAsciiNoCase(trimCpy(phrase), protoName + Zstr(":")))
+            if (startsWithAsciiNoCase(trimCpy(phrase), protoName + ':'))
                 throw FileError(replaceCpy(_("The %x protocol does not support directory monitoring:"), L"%x", utfTo<std::wstring>(protoName)) + L"\n\n" + fmtPath(phrase));
 
     for (;;)
diff --git a/FreeFileSync/Source/RealTimeSync/tray_menu.cpp b/FreeFileSync/Source/RealTimeSync/tray_menu.cpp
index a4c1a91a..09928566 100644
--- a/FreeFileSync/Source/RealTimeSync/tray_menu.cpp
+++ b/FreeFileSync/Source/RealTimeSync/tray_menu.cpp
@@ -91,7 +91,7 @@ public:
 
             case TRAY_MODE_WAITING:
                 assert(!missingFolderPath.empty());
-                setTrayIcon(greyScale(trayBmp_), _("Waiting until directory is available:") + L" " + fmtPath(missingFolderPath));
+                setTrayIcon(greyScale(trayBmp_), _("Waiting until directory is available:") + L' ' + fmtPath(missingFolderPath));
                 break;
 
             case TRAY_MODE_ERROR:
diff --git a/FreeFileSync/Source/afs/abstract.cpp b/FreeFileSync/Source/afs/abstract.cpp
index 9454f68b..10cb7995 100644
--- a/FreeFileSync/Source/afs/abstract.cpp
+++ b/FreeFileSync/Source/afs/abstract.cpp
@@ -399,7 +399,7 @@ void AFS::removeFileIfExists(const AbstractPath& ap) //throw FileError
             if (!AFS::itemStillExists(ap)) //throw FileError
                 return;
         }
-        catch (const FileError& e2) { throw FileError(replaceCpy(_("Cannot delete file %x."), L"%x", fmtPath(getDisplayPath(ap))), replaceCpy(e2.toString(), L"\n\n", L"\n")); }
+        catch (const FileError& e2) { throw FileError(replaceCpy(_("Cannot delete file %x."), L"%x", fmtPath(getDisplayPath(ap))), replaceCpy(e2.toString(), L"\n\n", L'\n')); }
         //more relevant than previous exception (which could be "item not found")
         throw;
     }
@@ -419,7 +419,7 @@ void AFS::removeSymlinkIfExists(const AbstractPath& ap) //throw FileError
             if (!AFS::itemStillExists(ap)) //throw FileError
                 return;
         }
-        catch (const FileError& e2) { throw FileError(replaceCpy(_("Cannot delete symbolic link %x."), L"%x", fmtPath(getDisplayPath(ap))), replaceCpy(e2.toString(), L"\n\n", L"\n")); }
+        catch (const FileError& e2) { throw FileError(replaceCpy(_("Cannot delete symbolic link %x."), L"%x", fmtPath(getDisplayPath(ap))), replaceCpy(e2.toString(), L"\n\n", L'\n')); }
         //more relevant than previous exception (which could be "item not found")
         throw;
     }
@@ -439,7 +439,7 @@ void AFS::removeEmptyFolderIfExists(const AbstractPath& ap) //throw FileError
             if (!AFS::itemStillExists(ap)) //throw FileError
                 return;
         }
-        catch (const FileError& e2) { throw FileError(replaceCpy(_("Cannot delete directory %x."), L"%x", fmtPath(getDisplayPath(ap))), replaceCpy(e2.toString(), L"\n\n", L"\n")); }
+        catch (const FileError& e2) { throw FileError(replaceCpy(_("Cannot delete directory %x."), L"%x", fmtPath(getDisplayPath(ap))), replaceCpy(e2.toString(), L"\n\n", L'\n')); }
         //more relevant than previous exception (which could be "item not found")
 
         throw;
diff --git a/FreeFileSync/Source/afs/abstract.h b/FreeFileSync/Source/afs/abstract.h
index bc4932b1..d48c5f87 100644
--- a/FreeFileSync/Source/afs/abstract.h
+++ b/FreeFileSync/Source/afs/abstract.h
@@ -79,7 +79,7 @@ struct AbstractFileSystem //THREAD-SAFETY: "const" member functions must model t
     static bool hasNativeTransactionalCopy(const AbstractPath& ap) { return ap.afsDevice.ref().hasNativeTransactionalCopy(); }
     //----------------------------------------------------------------------------------------------------------------
 
-    using FileId = zen::Zbase<char>; //AfsDevice-dependent unique ID
+    using FileId = std::string; //AfsDevice-dependent unique ID
 
     enum class ItemType : unsigned char
     {
@@ -497,8 +497,8 @@ void AbstractFileSystem::moveAndRenameItem(const AbstractPath& pathFrom, const A
         return pathFrom.afsDevice.ref().moveAndRenameItemForSameAfsType(pathFrom.afsPath, pathTo); //throw FileError, ErrorMoveUnsupported
 
     throw ErrorMoveUnsupported(replaceCpy(replaceCpy(_("Cannot move file %x to %y."),
-                                                     L"%x", L"\n" + fmtPath(getDisplayPath(pathFrom))),
-                                          L"%y", L"\n" + fmtPath(getDisplayPath(pathTo))), _("Operation not supported between different devices."));
+                                                     L"%x", L'\n' + fmtPath(getDisplayPath(pathFrom))),
+                                          L"%y", L'\n' + fmtPath(getDisplayPath(pathTo))), _("Operation not supported between different devices."));
 }
 
 
@@ -530,8 +530,8 @@ void AbstractFileSystem::copySymlink(const AbstractPath& apSource, const Abstrac
         return apSource.afsDevice.ref().copySymlinkForSameAfsType(apSource.afsPath, apTarget, copyFilePermissions); //throw FileError
 
     throw FileError(replaceCpy(replaceCpy(_("Cannot copy symbolic link %x to %y."),
-                                          L"%x", L"\n" + fmtPath(getDisplayPath(apSource))),
-                               L"%y", L"\n" + fmtPath(getDisplayPath(apTarget))), _("Operation not supported between different devices."));
+                                          L"%x", L'\n' + fmtPath(getDisplayPath(apSource))),
+                               L"%y", L'\n' + fmtPath(getDisplayPath(apTarget))), _("Operation not supported between different devices."));
 }
 }
 
diff --git a/FreeFileSync/Source/afs/abstract_impl.h b/FreeFileSync/Source/afs/abstract_impl.h
index c2d07828..ceabb6b6 100644
--- a/FreeFileSync/Source/afs/abstract_impl.h
+++ b/FreeFileSync/Source/afs/abstract_impl.h
@@ -123,7 +123,7 @@ public:
     size_t read(void* buffer, size_t bytesToRead) //throw <write error>
     {
         if (bytesToRead == 0) //"read() with a count of 0 returns zero" => indistinguishable from end of file! => check!
-            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + zen::numberTo<std::string>(__LINE__));
+            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + zen::numberTo<std::string>(__LINE__));
 
         auto       it    = static_cast<std::byte*>(buffer);
         const auto itEnd = it + bytesToRead;
diff --git a/FreeFileSync/Source/afs/ftp.cpp b/FreeFileSync/Source/afs/ftp.cpp
index e502936a..394c5966 100644
--- a/FreeFileSync/Source/afs/ftp.cpp
+++ b/FreeFileSync/Source/afs/ftp.cpp
@@ -104,8 +104,8 @@ Zstring ansiToUtfEncoding(const std::string& str) //throw SysError
         if (!error)
             throw SysError(L"g_convert: unknown error. (" + utfTo<std::wstring>(str) + L")"); //user should never see this
 
-        throw SysError(formatSystemError(L"g_convert", replaceCpy(_("Error Code %x"), L"%x", numberTo<std::wstring>(error->code)),
-                                         utfTo<std::wstring>(error->message)) + L" (" + utfTo<std::wstring>(str) + L")");
+        throw SysError(formatSystemError(L"g_convert(" + utfTo<std::wstring>(str) + L")",
+                                         replaceCpy(_("Error Code %x"), L"%x", numberTo<std::wstring>(error->code)), utfTo<std::wstring>(error->message)) );
     }
     ZEN_ON_SCOPE_EXIT(::g_free(utfStr));
 
@@ -134,8 +134,8 @@ std::string utfToAnsiEncoding(const Zstring& str) //throw SysError
         if (!error)
             throw SysError(L"g_convert: unknown error. (" + utfTo<std::wstring>(str) + L")"); //user should never see this
 
-        throw SysError(formatSystemError(L"g_convert", replaceCpy(_("Error Code %x"), L"%x", numberTo<std::wstring>(error->code)),
-                                         utfTo<std::wstring>(error->message)) + L" (" + utfTo<std::wstring>(str) + L")");
+        throw SysError(formatSystemError(L"g_convert(" + utfTo<std::wstring>(str) + L")",
+                                         replaceCpy(_("Error Code %x"), L"%x", numberTo<std::wstring>(error->code)), utfTo<std::wstring>(error->message)));
     }
     ZEN_ON_SCOPE_EXIT(::g_free(ansiStr));
 
@@ -239,7 +239,7 @@ private:
 
 //----------------------------------------------------------------------------------------------------------------
 
-std::wstring formatFtpStatusCode(int sc)
+std::wstring formatFtpStatus(int sc)
 {
     const wchar_t* statusText = [&] //https://en.wikipedia.org/wiki/List_of_FTP_server_return_codes
     {
@@ -495,7 +495,7 @@ public:
                     errorMsg += (errorMsg.empty() ? L"" : L"\n") + trimCpy(utfTo<std::wstring>(headerLines.back())); //that *should* be the servers error response
             }
             else //failed to get server response
-                errorMsg += (errorMsg.empty() ? L"" : L"\n") + formatFtpStatusCode(ftpStatusCode);
+                errorMsg += (errorMsg.empty() ? L"" : L"\n") + formatFtpStatus(ftpStatusCode);
 #if 0
             //utfTo<std::wstring>(::curl_easy_strerror(ec)) is uninteresting
             //use CURLINFO_OS_ERRNO ?? https://curl.haxx.se/libcurl/c/CURLINFO_OS_ERRNO.html
@@ -686,7 +686,7 @@ private:
             curl_socket_t currentSocket = 0;
             const CURLcode rc = ::curl_easy_getinfo(easyHandle_, CURLINFO_ACTIVESOCKET, &currentSocket);
             if (rc != CURLE_OK)
-                throw SysError(formatSystemError(L"curl_easy_getinfo: CURLINFO_ACTIVESOCKET", formatCurlStatusCode(rc), utfTo<std::wstring>(::curl_easy_strerror(rc))));
+                throw SysError(formatSystemError(L"curl_easy_getinfo(CURLINFO_ACTIVESOCKET)", formatCurlStatusCode(rc), utfTo<std::wstring>(::curl_easy_strerror(rc))));
             if (currentSocket != CURL_SOCKET_BAD)
                 return currentSocket;
         }
@@ -1288,7 +1288,7 @@ private:
         }
         catch (const SysError& e)
         {
-            throw SysError(L"Failed to parse FTP response. (" + utfTo<std::wstring>(rawLine) + L")" + (haveGroup ? L"" : L" [no-group]") + L" " + e.toString());
+            throw SysError(L"Failed to parse FTP response. (" + utfTo<std::wstring>(rawLine) + L")" + (haveGroup ? L"" : L" [no-group]") + L' ' + e.toString());
         }
     }
 
@@ -1769,7 +1769,7 @@ private:
         if (modTime_)
             try
             {
-                const std::string isoTime = formatTime<std::string>("%Y%m%d%H%M%S", getUtcTime(*modTime_)); //returns empty string on failure
+                const std::string isoTime = utfTo<std::string>(formatTime(Zstr("%Y%m%d%H%M%S"), getUtcTime(*modTime_))); //returns empty string on failure
                 if (isoTime.empty())
                     throw SysError(L"Invalid modification time (time_t: " + numberTo<std::wstring>(*modTime_) + L")");
 
@@ -1778,7 +1778,7 @@ private:
                     if (!session.supportsMfmt(login_.timeoutSec)) //throw SysError
                         throw SysError(L"Server does not support the MFMT command.");
 
-                    session.runSingleFtpCommand("MFMT " + isoTime + " " + session.getServerPathInternal(afsPath_, login_.timeoutSec),
+                    session.runSingleFtpCommand("MFMT " + isoTime + ' ' + session.getServerPathInternal(afsPath_, login_.timeoutSec),
                                                 true /*requiresUtf8*/, login_.timeoutSec); //throw SysError
                     //Does MFMT follow symlinks?? Anyway, our FTP implementation supports folder symlinks only
                 });
@@ -2040,8 +2040,8 @@ private:
     void copySymlinkForSameAfsType(const AfsPath& afsPathSource, const AbstractPath& apTarget, bool copyFilePermissions) const override
     {
         throw FileError(replaceCpy(replaceCpy(_("Cannot copy symbolic link %x to %y."),
-                                              L"%x", L"\n" + fmtPath(getDisplayPath(afsPathSource))),
-                                   L"%y", L"\n" + fmtPath(AFS::getDisplayPath(apTarget))), _("Operation not supported by device."));
+                                              L"%x", L'\n' + fmtPath(getDisplayPath(afsPathSource))),
+                                   L"%y", L'\n' + fmtPath(AFS::getDisplayPath(apTarget))), _("Operation not supported by device."));
     }
 
     //target existing: undefined behavior! (fail/overwrite/auto-rename)
@@ -2052,8 +2052,8 @@ private:
     void moveAndRenameItemForSameAfsType(const AfsPath& pathFrom, const AbstractPath& pathTo) const override //throw FileError, ErrorMoveUnsupported
     {
         auto generateErrorMsg = [&] { return replaceCpy(replaceCpy(_("Cannot move file %x to %y."),
-                                                                   L"%x", L"\n" + fmtPath(getDisplayPath(pathFrom))),
-                                                        L"%y", L"\n" + fmtPath(AFS::getDisplayPath(pathTo)));
+                                                                   L"%x", L'\n' + fmtPath(getDisplayPath(pathFrom))),
+                                                        L"%y", L'\n' + fmtPath(AFS::getDisplayPath(pathTo)));
                                     };
 
         if (compareDeviceSameAfsType(pathTo.afsDevice.ref()) != 0)
@@ -2121,7 +2121,7 @@ Zstring concatenateFtpFolderPathPhrase(const FtpLoginInfo& login, const AfsPath&
 {
     Zstring port;
     if (login.port > 0)
-        port = Zstr(":") + numberTo<Zstring>(login.port);
+        port = Zstr(':') + numberTo<Zstring>(login.port);
 
     Zstring options;
     if (login.timeoutSec != FtpLoginInfo().timeoutSec)
@@ -2182,11 +2182,11 @@ Zstring fff::condenseToFtpFolderPathPhrase(const FtpLoginInfo& login, const Zstr
 
     loginTmp.timeoutSec = std::max(1, loginTmp.timeoutSec);
 
-    if (startsWithAsciiNoCase(loginTmp.server, Zstr("http:" )) ||
-        startsWithAsciiNoCase(loginTmp.server, Zstr("https:")) ||
-        startsWithAsciiNoCase(loginTmp.server, Zstr("ftp:"  )) ||
-        startsWithAsciiNoCase(loginTmp.server, Zstr("ftps:" )) ||
-        startsWithAsciiNoCase(loginTmp.server, Zstr("sftp:" )))
+    if (startsWithAsciiNoCase(loginTmp.server, "http:" ) ||
+        startsWithAsciiNoCase(loginTmp.server, "https:") ||
+        startsWithAsciiNoCase(loginTmp.server, "ftp:"  ) ||
+        startsWithAsciiNoCase(loginTmp.server, "ftps:" ) ||
+        startsWithAsciiNoCase(loginTmp.server, "sftp:" ))
         loginTmp.server = afterFirst(loginTmp.server, Zstr(':'), IF_MISSING_RETURN_NONE);
     trim(loginTmp.server, true, false, [](Zchar c) { return c == Zstr('/') || c == Zstr('\\'); });
 
@@ -2211,7 +2211,7 @@ FtpPathInfo fff::getResolvedFtpPath(const Zstring& folderPathPhrase) //noexcept
     const Zstring fullPathOpt =  afterFirst(pathPhrase, Zstr('@'), IF_MISSING_RETURN_ALL);
 
     FtpLoginInfo login;
-    login.username = decodeFtpUsername(beforeFirst(credentials, Zstr(':'), IF_MISSING_RETURN_ALL)); //support standard FTP syntax, even though ":"
+    login.username = decodeFtpUsername(beforeFirst(credentials, Zstr(':'), IF_MISSING_RETURN_ALL)); //support standard FTP syntax, even though ':'
     login.password =                    afterFirst(credentials, Zstr(':'), IF_MISSING_RETURN_NONE); //is not used by our concatenateSftpFolderPathPhrase()!
 
     const Zstring fullPath = beforeFirst(fullPathOpt, Zstr('|'), IF_MISSING_RETURN_ALL);
diff --git a/FreeFileSync/Source/afs/ftp_common.h b/FreeFileSync/Source/afs/ftp_common.h
index edd3da54..c8fcff0a 100644
--- a/FreeFileSync/Source/afs/ftp_common.h
+++ b/FreeFileSync/Source/afs/ftp_common.h
@@ -35,9 +35,9 @@ inline
 Zstring encodeFtpUsername(Zstring name)
 {
     using namespace zen;
-    replace(name, Zstr("%"), Zstr("%25")); //first!
-    replace(name, Zstr("@"), Zstr("%40"));
-    replace(name, Zstr(":"), Zstr("%3A"));
+    replace(name, Zstr('%'), Zstr("%25")); //first!
+    replace(name, Zstr('@'), Zstr("%40"));
+    replace(name, Zstr(':'), Zstr("%3A"));
     return name;
 }
 
@@ -46,10 +46,10 @@ inline
 Zstring decodeFtpUsername(Zstring name)
 {
     using namespace zen;
-    replace(name, Zstr("%40"), Zstr("@"));
-    replace(name, Zstr("%3A"), Zstr(":"));
-    replace(name, Zstr("%3a"), Zstr(":"));
-    replace(name, Zstr("%25"), Zstr("%")); //last!
+    replace(name, Zstr("%40"), Zstr('@'));
+    replace(name, Zstr("%3A"), Zstr(':'));
+    replace(name, Zstr("%3a"), Zstr(':'));
+    replace(name, Zstr("%25"), Zstr('%')); //last!
     return name;
 }
 
diff --git a/FreeFileSync/Source/afs/gdrive.cpp b/FreeFileSync/Source/afs/gdrive.cpp
index 8c92eb47..467c40fe 100644
--- a/FreeFileSync/Source/afs/gdrive.cpp
+++ b/FreeFileSync/Source/afs/gdrive.cpp
@@ -294,7 +294,7 @@ HttpSession::Result googleHttpsRequest(const std::string& serverRelPath, //throw
         {
             //https://developers.google.com/drive/api/v3/performance
             //"In order to receive a gzip-encoded response you must do two things: Set an Accept-Encoding header, ["gzip" automatically set by HttpSession]
-            { CURLOPT_USERAGENT, "FreeFileSync (gzip)" }, // and modify your user agent to contain the string gzip."
+            { CURLOPT_USERAGENT, "FreeFileSync (gzip)" }, //and modify your user agent to contain the string gzip."
         };
         append(options, extraOptions);
 
@@ -547,7 +547,7 @@ for (;;) //::accept() blocks forever if no client connects (e.g. user just close
         const size_t blockSize = 64 * 1024;
         reqLine.resize(reqLine.size() + blockSize);
         const size_t bytesReceived = tryReadSocket(clientSocket, &*(reqLine.end() - blockSize), blockSize); //throw SysError
-        reqLine.resize(reqLine.size() - blockSize + bytesReceived); //caveat: unsigned arithmetics
+        reqLine.resize(reqLine.size() - (blockSize - bytesReceived)); //caveat: unsigned arithmetics
 
         if (contains(reqLine, "\r\n"))
         {
@@ -1058,7 +1058,7 @@ void gdriveMoveAndRenameItem(const std::string& itemId, const std::string& paren
     //more Google Drive peculiarities: changing the file name changes modifiedTime!!! => workaround:
 
     //RFC 3339 date-time: e.g. "2018-09-29T08:39:12.053Z"
-    const std::string modTimeRfc = formatTime<std::string>("%Y-%m-%dT%H:%M:%S.000Z", getUtcTime(newModTime)); //returns empty string on failure
+    const std::string modTimeRfc = utfTo<std::string>(formatTime(Zstr("%Y-%m-%dT%H:%M:%S.000Z"), getUtcTime(newModTime))); //returns empty string on failure
     if (modTimeRfc.empty())
         throw SysError(L"Invalid modification time (time_t: " + numberTo<std::wstring>(newModTime) + L")");
 
@@ -1250,7 +1250,7 @@ std::string /*itemId*/ gdriveUploadFile(const Zstring& fileName, const std::stri
         std::string postBuf = "{\n";
         if (modTime) //convert to RFC 3339 date-time: e.g. "2018-09-29T08:39:12.053Z"
         {
-            const std::string& modTimeRfc = formatTime<std::string>("%Y-%m-%dT%H:%M:%S.000Z", getUtcTime(*modTime)); //returns empty string on failure
+            const std::string& modTimeRfc = utfTo<std::string>(formatTime(Zstr("%Y-%m-%dT%H:%M:%S.000Z"), getUtcTime(*modTime))); //returns empty string on failure
             if (modTimeRfc.empty())
                 throw SysError(L"Invalid modification time (time_t: " + numberTo<std::wstring>(*modTime) + L")");
 
@@ -1345,7 +1345,7 @@ class GoogleAccessBuffer //per-user-session! => serialize access (perf: amortize
 public:
     GoogleAccessBuffer(const GoogleAccessInfo& accessInfo) : accessInfo_(accessInfo) {}
 
-    GoogleAccessBuffer(MemoryStreamIn<ByteArray>& stream) //throw UnexpectedEndOfStreamError
+    GoogleAccessBuffer(MemoryStreamIn<std::string>& stream) //throw UnexpectedEndOfStreamError
     {
         accessInfo_.accessToken.validUntil = readNumber<int64_t>(stream);                             //
         accessInfo_.accessToken.value      = readContainer<std::string>(stream);                      //
@@ -1354,7 +1354,7 @@ public:
         accessInfo_.userInfo.email         = utfTo<     Zstring>(readContainer<std::string>(stream)); //
     }
 
-    void serialize(MemoryStreamOut<ByteArray>& stream) const
+    void serialize(MemoryStreamOut<std::string>& stream) const
     {
         writeNumber<int64_t>(stream, accessInfo_.accessToken.validUntil);
         static_assert(sizeof(accessInfo_.accessToken.validUntil) <= sizeof(int64_t)); //ensure cross-platform compatibility!
@@ -1379,7 +1379,7 @@ public:
     void update(const GoogleAccessInfo& accessInfo)
     {
         if (!equalAsciiNoCase(accessInfo.userInfo.email, accessInfo_.userInfo.email))
-            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
         accessInfo_ = accessInfo;
     }
 
@@ -1402,7 +1402,7 @@ public:
         rootId_       (getRootItemId         (accessBuf.getAccessToken())), //throw SysError
         accessBuf_(accessBuf) {}                                            //
 
-    GoogleFileState(MemoryStreamIn<ByteArray>& stream, GoogleAccessBuffer& accessBuf, int dbVersion) : accessBuf_(accessBuf) //throw UnexpectedEndOfStreamError
+    GoogleFileState(MemoryStreamIn<std::string>& stream, GoogleAccessBuffer& accessBuf, int dbVersion) : accessBuf_(accessBuf) //throw UnexpectedEndOfStreamError
     {
         lastSyncToken_ = readContainer<std::string>(stream); //UnexpectedEndOfStreamError
         rootId_        = readContainer<std::string>(stream); //
@@ -1441,14 +1441,14 @@ public:
         }
     }
 
-    void serialize(MemoryStreamOut<ByteArray>& stream) const
+    void serialize(MemoryStreamOut<std::string>& stream) const
     {
         writeContainer(stream, lastSyncToken_);
         writeContainer(stream, rootId_);
 
         for (const auto& [folderId, content] : folderContents_)
             if (folderId.empty())
-                throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+                throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
             else if (content.isKnownFolder)
                 writeContainer(stream, folderId);
         writeContainer(stream, std::string()); //sentinel
@@ -1501,7 +1501,7 @@ public:
         const std::string fileId = getItemId(afsPath); //throw SysError
         auto it = itemDetails_.find(fileId);
         if (it == itemDetails_.end())
-            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
         return *it;
     }
 
@@ -1657,7 +1657,7 @@ private:
             notifyFolderContent(registerFileStateDelta(), folderId, readFolderContent(folderId, accessBuf_.getAccessToken())); //throw SysError
 
             if (!folderContents_[folderId].isKnownFolder)
-                throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+                throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
             childItems = &folderContents_[folderId].childItems;
         }
 
@@ -1668,7 +1668,7 @@ private:
             {
                 if (itFound != itemDetails_.end())
                     throw SysError(replaceCpy(_("Cannot find %x."), L"%x",
-                                              fmtPath(getGoogleDisplayPath({ accessBuf_.getUserEmail(), AfsPath(nativeAppendPaths(folderPath.value, relPath.front())) }))) + L" " +
+                                              fmtPath(getGoogleDisplayPath({ accessBuf_.getUserEmail(), AfsPath(nativeAppendPaths(folderPath.value, relPath.front())) }))) + L' ' +
                                    replaceCpy(_("The name %x is used by more than one item in the folder."), L"%x", fmtPath(relPath.front())));
 
                 itFound = itDetails;
@@ -1714,7 +1714,7 @@ private:
             if (it != itemDetails_.end()) //update
             {
                 if (it->second.isFolder != details->isFolder)
-                    throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__)); //WTF!?
+                    throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__)); //WTF!?
 
                 std::vector<std::string> parentIdsNew     = details->parentIds;
                 std::vector<std::string> parentIdsRemoved = it->second.parentIds;
@@ -1992,7 +1992,7 @@ private:
 
     static void saveSession(const Zstring& dbFilePath, const UserSession& userSession) //throw FileError
     {
-        MemoryStreamOut<ByteArray> streamOut;
+        MemoryStreamOut<std::string> streamOut;
 
         writeArray(streamOut, DB_FILE_DESCR, sizeof(DB_FILE_DESCR));
         writeNumber<int32_t>(streamOut, DB_FILE_VERSION);
@@ -2000,7 +2000,7 @@ private:
         userSession.accessBuf.ref().serialize(streamOut);
         userSession.fileState.ref().serialize(streamOut);
 
-        ByteArray zstreamOut;
+        std::string zstreamOut;
         try
         {
             zstreamOut = compress(streamOut.ref(), 3 /*compression level: see db_file.cpp*/); //throw SysError
@@ -2012,13 +2012,13 @@ private:
 
     static UserSession loadSession(const Zstring& dbFilePath) //throw FileError
     {
-        ByteArray zstream = loadBinContainer<ByteArray>(dbFilePath, nullptr /*notifyUnbufferedIO*/); //throw FileError
-        ByteArray rawStream;
+        const std::string zstream = loadBinContainer<std::string>(dbFilePath, nullptr /*notifyUnbufferedIO*/); //throw FileError
+        std::string rawStream;
         try
         {
             rawStream = decompress(zstream); //throw SysError
         }
-        catch (const SysError& e) { throw FileError(_("Database file is corrupted:") + L" " + fmtPath(dbFilePath), e.toString()); }
+        catch (const SysError& e) { throw FileError(_("Database file is corrupted:") + L' ' + fmtPath(dbFilePath), e.toString()); }
 
         MemoryStreamIn streamIn(rawStream);
         try
@@ -2041,7 +2041,7 @@ private:
             auto fileState = makeSharedRef<GoogleFileState   >(streamIn, accessBuf.ref(), version); //throw UnexpectedEndOfStreamError
             return { accessBuf, fileState };
         }
-        catch (UnexpectedEndOfStreamError&) { throw FileError(_("Database file is corrupted:") + L" " + fmtPath(dbFilePath), L"Unexpected end of stream."); }
+        catch (UnexpectedEndOfStreamError&) { throw FileError(_("Database file is corrupted:") + L' ' + fmtPath(dbFilePath), L"Unexpected end of stream."); }
     }
 
     struct UserSession
@@ -2162,7 +2162,7 @@ private:
             }
             else
             {
-                AFS::FileId fileId = copyStringTo<AFS::FileId>(item.itemId);
+                AFS::FileId fileId = item.itemId;
                 cb.onFile({ itemName, item.details.fileSize, item.details.modTime, fileId, nullptr /*symlinkInfo*/ }); //throw X
             }
         }
@@ -2245,7 +2245,7 @@ struct InputStreamGdrive : public AbstractFileSystem::InputStream
                 const auto& [itemId, gdriveAttr] = fileState.getFileAttributes(gdrivePath_.itemPath); //throw SysError
                 attr.modTime  = gdriveAttr.modTime;
                 attr.fileSize = gdriveAttr.fileSize;
-                attr.fileId   = copyStringTo<AFS::FileId>(itemId);
+                attr.fileId   = itemId;
             });
         }
         catch (const SysError& e) { throw FileError(replaceCpy(_("Cannot read file attributes of %x."), L"%x", fmtPath(getGoogleDisplayPath(gdrivePath_))), e.toString()); }
@@ -2336,7 +2336,7 @@ struct OutputStreamGdrive : public AbstractFileSystem::OutputStreamImpl
                         fileState.notifyItemCreated(aai.stateDelta, newFileItem);
                     });
 
-                    pFileId.set_value(copyStringTo<AFS::FileId>(fileIdNew));
+                    pFileId.set_value(fileIdNew);
                 }
                 catch (const SysError& e) { throw FileError(replaceCpy(_("Cannot write file %x."), L"%x", fmtPath(getGoogleDisplayPath(gdrivePath))), e.toString()); }
             }
@@ -2621,8 +2621,8 @@ private:
     void copySymlinkForSameAfsType(const AfsPath& afsPathSource, const AbstractPath& apTarget, bool copyFilePermissions) const override //throw FileError
     {
         throw FileError(replaceCpy(replaceCpy(_("Cannot copy symbolic link %x to %y."),
-                                              L"%x", L"\n" + fmtPath(getDisplayPath(afsPathSource))),
-                                   L"%y", L"\n" + fmtPath(AFS::getDisplayPath(apTarget))), _("Operation not supported by device."));
+                                              L"%x", L'\n' + fmtPath(getDisplayPath(afsPathSource))),
+                                   L"%y", L'\n' + fmtPath(AFS::getDisplayPath(apTarget))), _("Operation not supported by device."));
     }
 
     //target existing: undefined behavior! (fail/overwrite/auto-rename)
@@ -2630,8 +2630,8 @@ private:
     void moveAndRenameItemForSameAfsType(const AfsPath& pathFrom, const AbstractPath& pathTo) const override //throw FileError, ErrorMoveUnsupported
     {
         auto generateErrorMsg = [&] { return replaceCpy(replaceCpy(_("Cannot move file %x to %y."),
-                                                                   L"%x", L"\n" + fmtPath(getDisplayPath(pathFrom))),
-                                                        L"%y",  L"\n" + fmtPath(AFS::getDisplayPath(pathTo)));
+                                                                   L"%x", L'\n' + fmtPath(getDisplayPath(pathFrom))),
+                                                        L"%y",  L'\n' + fmtPath(AFS::getDisplayPath(pathTo)));
                                     };
 
         if (compareDeviceSameAfsType(pathTo.afsDevice.ref()) != 0)
diff --git a/FreeFileSync/Source/afs/native.cpp b/FreeFileSync/Source/afs/native.cpp
index da016788..6e1c96fc 100644
--- a/FreeFileSync/Source/afs/native.cpp
+++ b/FreeFileSync/Source/afs/native.cpp
@@ -118,8 +118,7 @@ std::vector<FsItemRaw> getDirContentFlat(const Zstring& dirPath) //throw FileErr
             (itemNameRaw[1] == 0 || (itemNameRaw[1] == '.' && itemNameRaw[2] == 0)))
             continue;
 
-        /*
-            Unicode normalization is file-system-dependent:
+        /* Unicode normalization is file-system-dependent:
 
                 OS                Accepts   Gives back
                ----------         -------   ----------
@@ -128,7 +127,7 @@ std::vector<FsItemRaw> getDirContentFlat(const Zstring& dirPath) //throw FileErr
                Windows (NTFS, FAT)  all      <input>
 
             some file systems return precomposed others decomposed UTF8: https://developer.apple.com/library/mac/#qa/qa1173/_index.html
-                  - OS X edit controls and text fields may return precomposed UTF as directly received by keyboard or decomposed UTF that was copy & pasted in!
+                  - OS X edit controls and text fields may return precomposed UTF as directly received by keyboard or decomposed UTF that was copy & pasted!
                   - Posix APIs require decomposed form: https://freefilesync.org/forum/viewtopic.php?t=2480
 
             => General recommendation: always preserve input UNCHANGED (both unicode normalization and case sensitivity)
@@ -556,8 +555,8 @@ private:
         //=> maybe we can even save some actual I/O in some cases?
         if (compareDeviceSameAfsType(pathTo.afsDevice.ref()) != 0)
             throw ErrorMoveUnsupported(replaceCpy(replaceCpy(_("Cannot move file %x to %y."),
-                                                             L"%x", L"\n" + fmtPath(getDisplayPath(pathFrom))),
-                                                  L"%y", L"\n" + fmtPath(AFS::getDisplayPath(pathTo))),
+                                                             L"%x", L'\n' + fmtPath(getDisplayPath(pathFrom))),
+                                                  L"%y", L'\n' + fmtPath(AFS::getDisplayPath(pathTo))),
                                        _("Operation not supported between different devices."));
         initComForThread(); //throw FileError
         const Zstring nativePathTarget = static_cast<const NativeFileSystem&>(pathTo.afsDevice.ref()).getNativePath(pathTo.afsPath);
@@ -639,7 +638,7 @@ void RecycleSessionNative::recycleItemIfExists(const AbstractPath& itemPath, con
 
     std::optional<Zstring> itemPathNative = AFS::getNativeItemPath(itemPath);
     if (!itemPathNative)
-        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
 
     recycleOrDeleteIfExists(*itemPathNative); //throw FileError
 }
@@ -658,7 +657,7 @@ bool fff::acceptsItemPathPhraseNative(const Zstring& itemPathPhrase) //noexcept
     trim(path);
 
 
-    if (startsWith(path, Zstr("["))) //drive letter by volume name syntax
+    if (startsWith(path, Zstr('['))) //drive letter by volume name syntax
         return true;
 
     //don't accept relative paths!!! indistinguishable from MTP paths as shown in Explorer's address bar!
diff --git a/FreeFileSync/Source/afs/sftp.cpp b/FreeFileSync/Source/afs/sftp.cpp
index d6279ebd..ed0ff13e 100644
--- a/FreeFileSync/Source/afs/sftp.cpp
+++ b/FreeFileSync/Source/afs/sftp.cpp
@@ -302,7 +302,7 @@ public:
                     }
                     else
                         throw SysError(replaceCpy(_("The server does not support authentication via %x."), L"%x", L"\"username/password\"") +
-                                       L"\n" +_("Required:") + L" " + utfTo<std::wstring>(authList));
+                                       L'\n' +_("Required:") + L' ' + utfTo<std::wstring>(authList));
                 }
                 break;
 
@@ -310,7 +310,7 @@ public:
                 {
                     if (!supportAuthKeyfile)
                         throw SysError(replaceCpy(_("The server does not support authentication via %x."), L"%x", L"\"key file\"") +
-                                       L"\n" +_("Required:") + L" " + utfTo<std::wstring>(authList));
+                                       L'\n' +_("Required:") + L' ' + utfTo<std::wstring>(authList));
 
                     std::string passphrase = passwordUtf8;
                     std::string pkStream;
@@ -365,9 +365,9 @@ public:
                             return nullptr; //other: maybe invalid, maybe not
                         }();
                         if (invalidKeyFormat)
-                            throw SysError(_("Authentication failed.") + L" " +
+                            throw SysError(_("Authentication failed.") + L' ' +
                                            replaceCpy<std::wstring>(L"%x is not an OpenSSH or PuTTY private key file.", L"%x",
-                                                                    fmtPath(sessionId_.privateKeyFilePath) + L" [" + invalidKeyFormat + L"]"));
+                                                                    fmtPath(sessionId_.privateKeyFilePath) + L" [" + invalidKeyFormat + L']'));
 
                         throw SysError(formatLastSshError(L"libssh2_userauth_publickey_frommemory", nullptr));
                     }
@@ -511,7 +511,7 @@ public:
         if (sshSessions.empty()) return;
 
         if (sshSessions.size() > FD_SETSIZE) //precise: this limit is for both fd_set containers *each*!
-            throw FatalSshError(_P("Cannot wait on more than 1 connection at a time.", "Cannot wait on more than %x connections at a time.", FD_SETSIZE) + L" " +
+            throw FatalSshError(_P("Cannot wait on more than 1 connection at a time.", "Cannot wait on more than %x connections at a time.", FD_SETSIZE) + L' ' +
                                 replaceCpy(_("Active connections: %x"), L"%x", numberTo<std::wstring>(sshSessions.size())));
         SocketType nfds = 0;
         fd_set rfd = {};
@@ -585,7 +585,7 @@ public:
         {
             if (sshSession.sftpChannels_.empty())
                 return msg;
-            return msg + L" " + replaceCpy(_("Failed to open SFTP channel number %x."), L"%x", numberTo<std::wstring>(sshSession.sftpChannels_.size() + 1));
+            return msg + L' ' + replaceCpy(_("Failed to open SFTP channel number %x."), L"%x", numberTo<std::wstring>(sshSession.sftpChannels_.size() + 1));
         };
 
         std::optional<SysError>      firstSysError;
@@ -1294,7 +1294,7 @@ private:
     {
         //libssh2_sftp_read has same semantics as Posix read:
         if (bytesToRead == 0) //"read() with a count of 0 returns zero" => indistinguishable from end of file! => check!
-            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
         assert(bytesToRead == getBlockSize());
 
         ssize_t bytesRead = 0;
@@ -1455,7 +1455,7 @@ private:
     size_t tryWrite(const void* buffer, size_t bytesToWrite) //throw FileError; may return short! CONTRACT: bytesToWrite > 0
     {
         if (bytesToWrite == 0)
-            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
         assert(bytesToWrite <= getBlockSize());
 
         ssize_t bytesWritten = 0;
@@ -1682,7 +1682,7 @@ private:
     std::string getSymlinkBinaryContent(const AfsPath& afsPath) const override //throw FileError
     {
         const unsigned int bufSize = 10000;
-        std::vector<char> buf(bufSize + 1); //ensure buffer is always null-terminated since we don't evaluate the byte count returned by libssh2_sftp_readlink()!
+        std::string buf(bufSize + 1, '\0'); //ensure buffer is always null-terminated since we don't evaluate the byte count returned by libssh2_sftp_readlink()!
         try
         {
             runSftpCommand(login_, L"libssh2_sftp_readlink", //throw SysError
@@ -1690,7 +1690,8 @@ private:
         }
         catch (const SysError& e) { throw FileError(replaceCpy(_("Cannot resolve symbolic link %x."), L"%x", fmtPath(getDisplayPath(afsPath))), e.toString()); }
 
-        return &buf[0];
+        buf.resize(strLength(&buf[0]));
+        return buf;
     }
     //----------------------------------------------------------------------------------------------------------------
 
@@ -1743,16 +1744,16 @@ private:
     void copySymlinkForSameAfsType(const AfsPath& afsPathSource, const AbstractPath& apTarget, bool copyFilePermissions) const override
     {
         throw FileError(replaceCpy(replaceCpy(_("Cannot copy symbolic link %x to %y."),
-                                              L"%x", L"\n" + fmtPath(getDisplayPath(afsPathSource))),
-                                   L"%y", L"\n" + fmtPath(AFS::getDisplayPath(apTarget))), _("Operation not supported by device."));
+                                              L"%x", L'\n' + fmtPath(getDisplayPath(afsPathSource))),
+                                   L"%y", L'\n' + fmtPath(AFS::getDisplayPath(apTarget))), _("Operation not supported by device."));
     }
 
     //target existing: undefined behavior! (fail/overwrite/auto-rename) => SFTP will fail with obscure LIBSSH2_FX_FAILURE error message
     void moveAndRenameItemForSameAfsType(const AfsPath& pathFrom, const AbstractPath& pathTo) const override //throw FileError, ErrorMoveUnsupported
     {
         auto generateErrorMsg = [&] { return replaceCpy(replaceCpy(_("Cannot move file %x to %y."),
-                                                                   L"%x", L"\n" + fmtPath(getDisplayPath(pathFrom))),
-                                                        L"%y", L"\n" + fmtPath(AFS::getDisplayPath(pathTo)));
+                                                                   L"%x", L'\n' + fmtPath(getDisplayPath(pathFrom))),
+                                                        L"%y", L'\n' + fmtPath(AFS::getDisplayPath(pathTo)));
                                     };
 
         if (compareDeviceSameAfsType(pathTo.afsDevice.ref()) != 0)
@@ -1849,7 +1850,7 @@ Zstring concatenateSftpFolderPathPhrase(const SftpLoginInfo& login, const AfsPat
 {
     Zstring port;
     if (login.port > 0)
-        port = Zstr(":") + numberTo<Zstring>(login.port);
+        port = Zstr(':') + numberTo<Zstring>(login.port);
 
     const SftpLoginInfo loginDefault;
 
@@ -1915,11 +1916,11 @@ Zstring fff::condenseToSftpFolderPathPhrase(const SftpLoginInfo& login, const Zs
     loginTmp.timeoutSec = std::max(1, loginTmp.timeoutSec);
     loginTmp.traverserChannelsPerConnection = std::max(1, loginTmp.traverserChannelsPerConnection);
 
-    if (startsWithAsciiNoCase(loginTmp.server, Zstr("http:" )) ||
-        startsWithAsciiNoCase(loginTmp.server, Zstr("https:")) ||
-        startsWithAsciiNoCase(loginTmp.server, Zstr("ftp:"  )) ||
-        startsWithAsciiNoCase(loginTmp.server, Zstr("ftps:" )) ||
-        startsWithAsciiNoCase(loginTmp.server, Zstr("sftp:" )))
+    if (startsWithAsciiNoCase(loginTmp.server, "http:" ) ||
+        startsWithAsciiNoCase(loginTmp.server, "https:") ||
+        startsWithAsciiNoCase(loginTmp.server, "ftp:"  ) ||
+        startsWithAsciiNoCase(loginTmp.server, "ftps:" ) ||
+        startsWithAsciiNoCase(loginTmp.server, "sftp:" ))
         loginTmp.server = afterFirst(loginTmp.server, Zstr(':'), IF_MISSING_RETURN_NONE);
     trim(loginTmp.server, true, false, [](Zchar c) { return c == Zstr('/') || c == Zstr('\\'); });
 
@@ -1948,7 +1949,7 @@ int fff::getServerMaxChannelsPerConnection(const SftpLoginInfo& login) //throw F
 
             if (numeric::dist(std::chrono::steady_clock::now(), startTime) > SFTP_CHANNEL_LIMIT_DETECTION_TIME_OUT)
                 throw SysError(_P("Operation timed out after 1 second.", "Operation timed out after %x seconds.",
-                                  std::chrono::seconds(SFTP_CHANNEL_LIMIT_DETECTION_TIME_OUT).count()) + L" " +
+                                  std::chrono::seconds(SFTP_CHANNEL_LIMIT_DETECTION_TIME_OUT).count()) + L' ' +
                                replaceCpy(_("Failed to open SFTP channel number %x."), L"%x", numberTo<std::wstring>(exSession->getSftpChannelCount() + 1)));
         }
     }
@@ -1976,7 +1977,7 @@ SftpPathInfo fff::getResolvedSftpPath(const Zstring& folderPathPhrase) //noexcep
     const Zstring fullPathOpt =  afterFirst(pathPhrase, Zstr('@'), IF_MISSING_RETURN_ALL);
 
     SftpLoginInfo login;
-    login.username = decodeFtpUsername(beforeFirst(credentials, Zstr(':'), IF_MISSING_RETURN_ALL)); //support standard FTP syntax, even though ":"
+    login.username = decodeFtpUsername(beforeFirst(credentials, Zstr(':'), IF_MISSING_RETURN_ALL)); //support standard FTP syntax, even though ':'
     login.password =                    afterFirst(credentials, Zstr(':'), IF_MISSING_RETURN_NONE); //is not used by our concatenateSftpFolderPathPhrase()!
 
     const Zstring fullPath = beforeFirst(fullPathOpt, Zstr('|'), IF_MISSING_RETURN_ALL);
diff --git a/FreeFileSync/Source/base/application.cpp b/FreeFileSync/Source/application.cpp
index 657eac13..65755b0e 100644
--- a/FreeFileSync/Source/base/application.cpp
+++ b/FreeFileSync/Source/application.cpp
@@ -15,17 +15,18 @@
 #include <wx+/popup_dlg.h>
 #include <wx+/image_resources.h>
 #include <wx/msgdlg.h>
-#include "comparison.h"
+#include "afs/concrete.h"
+#include "base/algorithm.h"
+#include "base/comparison.h"
+#include "base/resolve_path.h"
+#include "base/synchronization.h"
+#include "ui/batch_status_handler.h"
+#include "ui/main_dlg.h"
+#include "base_tools.h"
 #include "config.h"
-#include "algorithm.h"
-#include "synchronization.h"
 #include "help_provider.h"
 #include "fatal_error.h"
 #include "log_file.h"
-#include "resolve_path.h"
-#include "../ui/batch_status_handler.h"
-#include "../ui/main_dlg.h"
-#include "../afs/concrete.h"
 
     #include <gtk/gtk.h>
 
@@ -84,14 +85,15 @@ bool Application::OnInit()
                                           (getResourceDirPf() + "Gtk3Styles.css").c_str(), //const gchar* path,
                                           &error); //GError** error
         if (error)
-            throw SysError(formatSystemError(L"gtk_css_provider_load_from_data",
-                                             replaceCpy(_("Error Code %x"), L"%x", numberTo<std::wstring>(error->code)), utfTo<std::wstring>(error->message)));
+            throw SysError(formatSystemError(L"gtk_css_provider_load_from_data", replaceCpy(_("Error Code %x"), L"%x",
+                                                                                            numberTo<std::wstring>(error->code)),
+                                             utfTo<std::wstring>(error->message)));
 
         ::gtk_style_context_add_provider_for_screen(::gdk_screen_get_default(),               //GdkScreen* screen,
                                                     GTK_STYLE_PROVIDER(provider),             //GtkStyleProvider* provider,
                                                     GTK_STYLE_PROVIDER_PRIORITY_APPLICATION); //guint priority
     }
-    catch (const SysError& e) { std::cerr << utfTo<std::string>(e.toString()) << "\n"; }
+    catch (const SysError& e) { std::cerr << utfTo<std::string>(e.toString()) << '\n'; }
 #else
 #error unknown GTK version!
 #endif
@@ -160,7 +162,7 @@ int Application::OnRun()
         logFatalError(e.what()); //it's not always possible to display a message box, e.g. corrupted stack, however low-level file output works!
 
         const auto titleFmt = copyStringTo<std::wstring>(wxTheApp->GetAppDisplayName()) + SPACED_DASH + _("An exception occurred");
-        std::cerr << utfTo<std::string>(titleFmt + SPACED_DASH) << e.what() << "\n";
+        std::cerr << utfTo<std::string>(titleFmt + SPACED_DASH) << e.what() << '\n';
         return FFS_RC_EXCEPTION;
     }
     //catch (...) -> let it crash and create mini dump!!!
@@ -197,7 +199,7 @@ void Application::launch(const std::vector<Zstring>& commandArgs)
 
         //error handling strategy unknown and no sync log output available at this point!
         auto titleFmt = copyStringTo<std::wstring>(wxTheApp->GetAppDisplayName()) + SPACED_DASH + title;
-        std::cerr << utfTo<std::string>(titleFmt + SPACED_DASH + msg) << "\n";
+        std::cerr << utfTo<std::string>(titleFmt + SPACED_DASH + msg) << '\n';
         //alternative0: std::wcerr: cannot display non-ASCII at all, so why does it exist???
         //alternative1: wxSafeShowMessage => NO console output on Debian x86, WTF!
         //alternative2: wxMessageBox() => works, but we probably shouldn't block during command line usage
@@ -210,9 +212,9 @@ void Application::launch(const std::vector<Zstring>& commandArgs)
     Zstring globalConfigFile;
     bool openForEdit = false;
     {
-        const Zchar* optionEdit    = Zstr("-edit");
-        const Zchar* optionDirPair = Zstr("-dirpair");
-        const Zchar* optionSendTo  = Zstr("-sendto"); //remaining arguments are unspecified number of folder paths; wonky syntax; let's keep it undocumented
+        const char* optionEdit    = "-edit";
+        const char* optionDirPair = "-dirpair";
+        const char* optionSendTo  = "-sendto"; //remaining arguments are unspecified number of folder paths; wonky syntax; let's keep it undocumented
 
         auto isHelpRequest = [](const Zstring& arg)
         {
@@ -220,8 +222,8 @@ void Application::launch(const std::vector<Zstring>& commandArgs)
             if (it == arg.begin()) return false; //require at least one prefix character
 
             const Zstring argTmp(it, arg.end());
-            return equalAsciiNoCase(argTmp, Zstr("help")) ||
-                   equalAsciiNoCase(argTmp, Zstr("h"))    ||
+            return equalAsciiNoCase(argTmp, "help") ||
+                   equalAsciiNoCase(argTmp, "h")    ||
                    argTmp == Zstr("?");
         };
 
@@ -473,23 +475,23 @@ void showSyntaxHelp()
     showNotificationDialog(nullptr, DialogInfoType::info, PopupDialogCfg().
                            setTitle(_("Command line")).
                            setDetailInstructions(_("Syntax:") + L"\n\n" +
-                                                 L"./FreeFileSync" + L"\n" +
-                                                 L"    [" + _("config files:") + L" *.ffs_gui/*.ffs_batch]" + L"\n" +
-                                                 L"    [-DirPair " + _("directory") + L" " + _("directory") + L"]" + L"\n" +
-                                                 L"    [-Edit]" + L"\n" +
-                                                 L"    [" + _("global config file:") + L" GlobalSettings.xml]" + L"\n" +
+                                                 L"./FreeFileSync" + L'\n' +
+                                                 L"    [" + _("config files:") + L" *.ffs_gui/*.ffs_batch]" + L'\n' +
+                                                 L"    [-DirPair " + _("directory") + L' ' + _("directory") + L"]" L"\n" +
+                                                 L"    [-Edit]" + L'\n' +
+                                                 L"    [" + _("global config file:") + L" GlobalSettings.xml]" + L"\n"
                                                  L"\n" +
 
-                                                 _("config files:") + L"\n" +
+                                                 _("config files:") + L'\n' +
                                                  _("Any number of FreeFileSync \"ffs_gui\" and/or \"ffs_batch\" configuration files.") + L"\n\n" +
 
-                                                 L"-DirPair " + _("directory") + L" " + _("directory") + L"\n" +
+                                                 L"-DirPair " + _("directory") + L' ' + _("directory") + L'\n' +
                                                  _("Any number of alternative directory pairs for at most one config file.") + L"\n\n" +
 
-                                                 L"-Edit" + L"\n" +
+                                                 L"-Edit" + "\n" +
                                                  _("Open the selected configuration for editing only, without executing it.") + L"\n\n" +
 
-                                                 _("global config file:") + L"\n" +
+                                                 _("global config file:") + L'\n' +
                                                  _("Path to an alternate GlobalSettings.xml file.")));
 }
 
@@ -596,7 +598,7 @@ void runBatchMode(const Zstring& globalConfigFilePath, const XmlBatchConfig& bat
     catch (AbortProcess&) {} //exit used by statusHandler
 
     BatchStatusHandler::Result r = statusHandler.reportResults(batchCfg.mainCfg.postSyncCommand, batchCfg.mainCfg.postSyncCondition,
-                                                               batchCfg.mainCfg.altLogFolderPathPhrase, globalCfg.logfilesMaxAgeDays, logFilePathsToKeep,
+                                                               batchCfg.mainCfg.altLogFolderPathPhrase, globalCfg.logfilesMaxAgeDays, globalCfg.logFormat, logFilePathsToKeep,
                                                                batchCfg.mainCfg.emailNotifyAddress, batchCfg.mainCfg.emailNotifyCondition); //noexcept
     //----------------------------------------------------------------------
 
diff --git a/FreeFileSync/Source/base/application.h b/FreeFileSync/Source/application.h
index a52e6617..a52e6617 100644
--- a/FreeFileSync/Source/base/application.h
+++ b/FreeFileSync/Source/application.h
diff --git a/FreeFileSync/Source/base/algorithm.cpp b/FreeFileSync/Source/base/algorithm.cpp
index ddb449d6..2b66e9a5 100644
--- a/FreeFileSync/Source/base/algorithm.cpp
+++ b/FreeFileSync/Source/base/algorithm.cpp
@@ -712,9 +712,9 @@ private:
         recurse(folder, dbEntryL, dbEntryR);
     }
 
-    const std::wstring txtBothSidesChanged_ = _("Both sides have changed since last synchronization.");
-    const std::wstring txtNoSideChanged_    = _("Cannot determine sync-direction:") + L" \n" + _("No change since last synchronization.");
-    const std::wstring txtDbNotInSync_      = _("Cannot determine sync-direction:") + L" \n" + _("The database entry is not in sync considering current settings.");
+    const Zstringc txtBothSidesChanged_ = utfTo<Zstringc>(_("Both sides have changed since last synchronization."));
+    const Zstringc txtNoSideChanged_    = utfTo<Zstringc>(_("Cannot determine sync-direction:") + L" \n" + _("No change since last synchronization."));
+    const Zstringc txtDbNotInSync_      = utfTo<Zstringc>(_("Cannot determine sync-direction:") + L" \n" + _("The database entry is not in sync considering current settings."));
 
     const CompareVariant cmpVar_;
     const int fileTimeTolerance_;
@@ -736,7 +736,7 @@ std::vector<std::pair<BaseFolderPair*, DirectionConfig>> fff::extractDirectionCf
                     mainCfg.additionalPairs.end());
 
     if (folderCmp.size() != allPairs.size())
-        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
 
     std::vector<std::pair<BaseFolderPair*, DirectionConfig>> output;
 
@@ -779,7 +779,7 @@ void fff::redetermineSyncDirection(const std::vector<std::pair<BaseFolderPair*,
 					{
 						std::wstring msg = _("Setting default synchronization directions: Old files will be overwritten with newer files.");
 						if (directCfgs.size() > 1)
-							msg += "\n" + AFS::getDisplayPath(baseFolder->getAbstractPath< LEFT_SIDE>()) + L" " + getVariantNameForLog(dirCfg.var) + L" " +
+							msg += L'\n' + AFS::getDisplayPath(baseFolder->getAbstractPath< LEFT_SIDE>()) + L' ' + getVariantNameForLog(dirCfg.var) + L' ' +
 										  AFS::getDisplayPath(baseFolder->getAbstractPath<RIGHT_SIDE>());
 
 						try { callback.reportInfo(msg); /*throw X*/} catch (...) {};
@@ -1089,7 +1089,7 @@ void fff::applyFiltering(FolderComparison& folderCmp, const MainConfiguration& m
     if (folderCmp.empty())
         return;
     else if (folderCmp.size() != mainCfg.additionalPairs.size() + 1)
-        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
 
     //merge first and additional pairs
     std::vector<LocalPairConfig> allPairs;
@@ -1610,11 +1610,11 @@ void fff::deleteFromGridAndHD(const std::vector<FileSystemObject*>& rowsToDelete
     if (useRecycleBin &&
     std::any_of(recyclerSupported.begin(), recyclerSupported.end(), [](const auto& item) { return !item.second; }))
     {
-        std::wstring msg = _("The recycle bin is not supported by the following folders. Deleted or overwritten files will not be able to be restored:") + L"\n";
+        std::wstring msg = _("The recycle bin is not supported by the following folders. Deleted or overwritten files will not be able to be restored:") + L'\n';
 
         for (const auto& [folderPath, supported] : recyclerSupported)
             if (!supported)
-                msg += L"\n" + AFS::getDisplayPath(folderPath);
+                msg += L'\n' + AFS::getDisplayPath(folderPath);
 
         callback.reportWarning(msg, warnRecyclerMissing); //throw?
     }
diff --git a/FreeFileSync/Source/base/algorithm.h b/FreeFileSync/Source/base/algorithm.h
index 299a97a0..48d8b7c1 100644
--- a/FreeFileSync/Source/base/algorithm.h
+++ b/FreeFileSync/Source/base/algorithm.h
@@ -8,7 +8,8 @@
 #define ALGORITHM_H_34218518475321452548
 
 #include <functional>
-#include "config.h"
+//#include "config.h"
+#include "structures.h"
 #include "file_hierarchy.h"
 #include "soft_filter.h"
 #include "process_callback.h"
diff --git a/FreeFileSync/Source/base/binary.cpp b/FreeFileSync/Source/base/binary.cpp
index db5dee54..f3199f67 100644
--- a/FreeFileSync/Source/base/binary.cpp
+++ b/FreeFileSync/Source/base/binary.cpp
@@ -137,7 +137,7 @@ bool fff::filesHaveSameContent(const AbstractPath& filePath1, const AbstractPath
     }
 
     if (totalUnbufferedIO % 2 != 0)
-        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
 
     return true;
 }
diff --git a/FreeFileSync/Source/base/comparison.cpp b/FreeFileSync/Source/base/comparison.cpp
index e705551b..27e23867 100644
--- a/FreeFileSync/Source/base/comparison.cpp
+++ b/FreeFileSync/Source/base/comparison.cpp
@@ -103,14 +103,14 @@ ResolvedBaseFolders initializeBaseFolders(const std::vector<FolderPairCfg>& fpCf
 
         if (!status.failedChecks.empty())
         {
-            std::wstring msg = _("Cannot find the following folders:") + L"\n";
+            std::wstring msg = _("Cannot find the following folders:") + L'\n';
 
             for (const auto& [folderPath, error] : status.failedChecks)
-                msg += L"\n" + AFS::getDisplayPath(folderPath);
+                msg += L'\n' + AFS::getDisplayPath(folderPath);
 
             msg += L"\n___________________________________________";
             for (const auto& [folderPath, error] : status.failedChecks)
-                msg += L"\n\n" + replaceCpy(error.toString(), L"\n\n", L"\n");
+                msg += L"\n\n" + replaceCpy(error.toString(), L"\n\n", L'\n');
 
             throw FileError(msg);
         }
@@ -119,10 +119,10 @@ ResolvedBaseFolders initializeBaseFolders(const std::vector<FolderPairCfg>& fpCf
 
     if (!notExisting.empty())
     {
-        std::wstring msg = _("The following folders do not yet exist:") + L"\n";
+        std::wstring msg = _("The following folders do not yet exist:") + L'\n';
 
         for (const AbstractPath& folderPath : notExisting)
-            msg += L"\n" + AFS::getDisplayPath(folderPath);
+            msg += L'\n' + AFS::getDisplayPath(folderPath);
 
         msg += L"\n\n";
         msg +=  _("The folders are created automatically when needed.");
@@ -142,9 +142,9 @@ ResolvedBaseFolders initializeBaseFolders(const std::vector<FolderPairCfg>& fpCf
         for (const auto& [key, aliases] : ciPathAliases)
             if (aliases.size() > 1)
             {
-                msg += L"\n";
+                msg += L'\n';
                 for (const AbstractPath& aliasPath : aliases)
-                    msg += L"\n" + AFS::getDisplayPath(aliasPath);
+                    msg += L'\n' + AFS::getDisplayPath(aliasPath);
             }
 
         callback.reportWarning(msg, warnings.warnFoldersDifferInCase); //throw X
@@ -204,7 +204,7 @@ ComparisonBuffer::ComparisonBuffer(const std::set<DirectoryKey>& foldersToRead,
     const std::chrono::steady_clock::time_point compareStartTime = std::chrono::steady_clock::now();
     int itemsReported = 0;
 
-    auto onStatusUpdate = [&, textScanning = _("Scanning:") + L" "](const std::wstring& statusLine, int itemsTotal)
+    auto onStatusUpdate = [&, textScanning = _("Scanning:") + L' '](const std::wstring& statusLine, int itemsTotal)
     {
         callback.updateDataProcessed(itemsTotal - itemsReported, 0); //noexcept
         itemsReported = itemsTotal;
@@ -219,9 +219,9 @@ ComparisonBuffer::ComparisonBuffer(const std::set<DirectoryKey>& foldersToRead,
 
     const int64_t totalTimeSec = std::chrono::duration_cast<std::chrono::seconds>(std::chrono::steady_clock::now() - compareStartTime).count();
 
-    callback.reportInfo(_("Comparison finished:") + L" " +
+    callback.reportInfo(_("Comparison finished:") + L' ' +
                         _P("1 item found", "%x items found", itemsReported) + L" | " +
-                        _("Time elapsed:") + L" " + copyStringTo<std::wstring>(wxTimeSpan::Seconds(totalTimeSec).Format())); //throw X
+                        _("Time elapsed:") + L' ' + copyStringTo<std::wstring>(wxTimeSpan::Seconds(totalTimeSec).Format())); //throw X
 }
 
 
@@ -236,49 +236,49 @@ const wchar_t arrowRight[] = L"->";
 //      => only add path info if information is relevant, e.g. conflict is specific to left/right side only
 
 template <SelectedSide side, class FileOrLinkPair> inline
-Zstringw getConflictInvalidDate(const FileOrLinkPair& file)
+Zstringc getConflictInvalidDate(const FileOrLinkPair& file)
 {
-    return copyStringTo<Zstringw>(replaceCpy(_("File %x has an invalid date."), L"%x", fmtPath(AFS::getDisplayPath(file.template getAbstractPath<side>()))) + L"\n" +
-                                  _("Date:") + L" " + formatUtcToLocalTime(file.template getLastWriteTime<side>()));
+    return utfTo<Zstringc>(replaceCpy(_("File %x has an invalid date."), L"%x", fmtPath(AFS::getDisplayPath(file.template getAbstractPath<side>()))) + L'\n' +
+                           _("Date:") + L' ' + formatUtcToLocalTime(file.template getLastWriteTime<side>()));
 }
 
 
-Zstringw getConflictSameDateDiffSize(const FilePair& file)
+Zstringc getConflictSameDateDiffSize(const FilePair& file)
 {
-    return copyStringTo<Zstringw>(_("Files have the same date but a different size.") + L"\n" +
-                                  arrowLeft  + L" " + _("Date:") + L" " + formatUtcToLocalTime(file.getLastWriteTime< LEFT_SIDE>()) + L"    " + _("Size:") + L" " + formatNumber(file.getFileSize<LEFT_SIDE>()) + L"\n" +
-                                  arrowRight + L" " + _("Date:") + L" " + formatUtcToLocalTime(file.getLastWriteTime<RIGHT_SIDE>()) + L"    " + _("Size:") + L" " + formatNumber(file.getFileSize<RIGHT_SIDE>()));
+    return utfTo<Zstringc>(_("Files have the same date but a different size.") + L'\n' +
+                           arrowLeft  + L' ' + _("Date:") + L' ' + formatUtcToLocalTime(file.getLastWriteTime< LEFT_SIDE>()) + L"    " + _("Size:") + L' ' + formatNumber(file.getFileSize<LEFT_SIDE>()) + L'\n' +
+                           arrowRight + L' ' + _("Date:") + L' ' + formatUtcToLocalTime(file.getLastWriteTime<RIGHT_SIDE>()) + L"    " + _("Size:") + L' ' + formatNumber(file.getFileSize<RIGHT_SIDE>()));
 }
 
 
-Zstringw getConflictSkippedBinaryComparison()
+Zstringc getConflictSkippedBinaryComparison()
 {
-    return copyStringTo<Zstringw>(_("Content comparison was skipped for excluded files."));
+    return utfTo<Zstringc>(_("Content comparison was skipped for excluded files."));
 }
 
 
-Zstringw getDescrDiffMetaShortnameCase(const FileSystemObject& fsObj)
+Zstringc getDescrDiffMetaShortnameCase(const FileSystemObject& fsObj)
 {
-    return copyStringTo<Zstringw>(_("Items differ in attributes only") + L"\n" +
-                                  arrowLeft  + L" " + fmtPath(fsObj.getItemName< LEFT_SIDE>()) + L"\n" +
-                                  arrowRight + L" " + fmtPath(fsObj.getItemName<RIGHT_SIDE>()));
+    return utfTo<Zstringc>(_("Items differ in attributes only") + L'\n' +
+                           arrowLeft  + L' ' + fmtPath(fsObj.getItemName< LEFT_SIDE>()) + L'\n' +
+                           arrowRight + L' ' + fmtPath(fsObj.getItemName<RIGHT_SIDE>()));
 }
 
 
 #if 0
 template <class FileOrLinkPair>
-Zstringw getDescrDiffMetaData(const FileOrLinkPair& file)
+Zstringc getDescrDiffMetaData(const FileOrLinkPair& file)
 {
-    return copyStringTo<Zstringw>(_("Items differ in attributes only") + L"\n" +
-                                  arrowLeft  + L" " + _("Date:") + L" " + formatUtcToLocalTime(file.template getLastWriteTime< LEFT_SIDE>()) + L"\n" +
-                                  arrowRight + L" " + _("Date:") + L" " + formatUtcToLocalTime(file.template getLastWriteTime<RIGHT_SIDE>()));
+    return utfTo<Zstringc>(_("Items differ in attributes only") + L'\n' +
+                           arrowLeft  + L' ' + _("Date:") + L' ' + formatUtcToLocalTime(file.template getLastWriteTime< LEFT_SIDE>()) + L'\n' +
+                           arrowRight + L' ' + _("Date:") + L' ' + formatUtcToLocalTime(file.template getLastWriteTime<RIGHT_SIDE>()));
 }
 #endif
 
 
-Zstringw getConflictAmbiguousItemName(const Zstring& itemName)
+Zstringc getConflictAmbiguousItemName(const Zstring& itemName)
 {
-    return copyStringTo<Zstringw>(replaceCpy(_("The name %x is used by more than one item in the folder."), L"%x", fmtPath(itemName)));
+    return utfTo<Zstringc>(replaceCpy(_("The name %x is used by more than one item in the folder."), L"%x", fmtPath(itemName)));
 }
 
 //-----------------------------------------------------------------------------
@@ -392,7 +392,7 @@ void categorizeSymlinkByContent(SymlinkPair& symlink, PhaseCallback& callback)
     }, callback); //throw X
 
     if (!errMsg.empty())
-        symlink.setCategoryConflict(copyStringTo<Zstringw>(errMsg));
+        symlink.setCategoryConflict(utfTo<Zstringc>(errMsg));
     else
     {
         if (binaryContentL == binaryContentR)
@@ -489,7 +489,7 @@ void categorizeFileByContent(FilePair& file, const std::wstring& txtComparingCon
     }, acb); //throw ThreadInterruption
 
     if (!errMsg.empty())
-        file.setCategoryConflict(copyStringTo<Zstringw>(errMsg));
+        file.setCategoryConflict(utfTo<Zstringc>(errMsg));
     else
     {
         if (haveSameContent)
@@ -542,7 +542,7 @@ std::list<std::shared_ptr<BaseFolderPair>> ComparisonBuffer::compareByContent(co
     //PERF_START;
     std::list<std::shared_ptr<BaseFolderPair>> output;
 
-    const Zstringw txtConflictSkippedBinaryComparison = getConflictSkippedBinaryComparison(); //avoid premature pess.: save memory via ref-counted string
+    const Zstringc txtConflictSkippedBinaryComparison = getConflictSkippedBinaryComparison(); //avoid premature pess.: save memory via ref-counted string
 
     for (const auto& [folderPair, fpCfg] : workLoad)
     {
@@ -654,7 +654,7 @@ std::list<std::shared_ptr<BaseFolderPair>> ComparisonBuffer::compareByContent(co
 class MergeSides
 {
 public:
-    MergeSides(const std::map<ZstringNoCase, Zstringw>& errorsByRelPath,
+    MergeSides(const std::map<ZstringNoCase, Zstringc>& errorsByRelPath,
                std::vector<FilePair*>& undefinedFilesOut,
                std::vector<SymlinkPair*>& undefinedSymlinksOut) :
         errorsByRelPath_(errorsByRelPath),
@@ -671,21 +671,21 @@ public:
     }
 
 private:
-    void mergeTwoSides(const FolderContainer& lhs, const FolderContainer& rhs, const Zstringw* errorMsg, ContainerObject& output);
+    void mergeTwoSides(const FolderContainer& lhs, const FolderContainer& rhs, const Zstringc* errorMsg, ContainerObject& output);
 
     template <SelectedSide side>
-    void fillOneSide(const FolderContainer& folderCont, const Zstringw* errorMsg, ContainerObject& output);
+    void fillOneSide(const FolderContainer& folderCont, const Zstringc* errorMsg, ContainerObject& output);
 
-    const Zstringw* checkFailedRead(FileSystemObject& fsObj, const Zstringw* errorMsg);
+    const Zstringc* checkFailedRead(FileSystemObject& fsObj, const Zstringc* errorMsg);
 
-    const std::map<ZstringNoCase, Zstringw>& errorsByRelPath_; //base-relative paths or empty if read-error for whole base directory
+    const std::map<ZstringNoCase, Zstringc>& errorsByRelPath_; //base-relative paths or empty if read-error for whole base directory
     std::vector<FilePair*>&    undefinedFiles_;
     std::vector<SymlinkPair*>& undefinedSymlinks_;
 };
 
 
 inline
-const Zstringw* MergeSides::checkFailedRead(FileSystemObject& fsObj, const Zstringw* errorMsg)
+const Zstringc* MergeSides::checkFailedRead(FileSystemObject& fsObj, const Zstringc* errorMsg)
 {
     if (!errorMsg)
     {
@@ -697,15 +697,15 @@ const Zstringw* MergeSides::checkFailedRead(FileSystemObject& fsObj, const Zstri
     if (errorMsg)
     {
         fsObj.setActive(false);
-        fsObj.setCategoryConflict(*errorMsg); //peak memory: Zstringw is ref-counted, unlike std::wstring!
-        static_assert(std::is_same_v<const Zstringw&, decltype(*errorMsg)>);
+        fsObj.setCategoryConflict(*errorMsg); //peak memory: Zstringc is ref-counted, unlike std::string!
+        static_assert(std::is_same_v<const Zstringc&, decltype(*errorMsg)>);
     }
     return errorMsg;
 }
 
 
 template <SelectedSide side>
-void MergeSides::fillOneSide(const FolderContainer& folderCont, const Zstringw* errorMsg, ContainerObject& output)
+void MergeSides::fillOneSide(const FolderContainer& folderCont, const Zstringc* errorMsg, ContainerObject& output)
 {
     for (const auto& [fileName, attrib] : folderCont.files)
     {
@@ -722,7 +722,7 @@ void MergeSides::fillOneSide(const FolderContainer& folderCont, const Zstringw*
     for (const auto& [folderName, attrAndSub] : folderCont.folders)
     {
         FolderPair& newFolder = output.addSubFolder<side>(folderName, attrAndSub.first);
-        const Zstringw* errorMsgNew = checkFailedRead(newFolder, errorMsg);
+        const Zstringc* errorMsgNew = checkFailedRead(newFolder, errorMsg);
         fillOneSide<side>(attrAndSub.second, errorMsgNew, newFolder); //recurse
     }
 }
@@ -783,7 +783,7 @@ void matchFolders(const MapType& mapLeft, const MapType& mapRight, ProcessLeftOn
                 auto itEndCase = std::find_if(itCase + 1, itEndEq, [&](const FileRef& fr) { return getUnicodeNormalForm(fr.ref->first) != getUnicodeNormalForm(itCase->ref->first); });
                 if (!tryMatchRange(itCase, itEndCase))
                 {
-                    const Zstringw& conflictMsg = getConflictAmbiguousItemName(itCase->ref->first);
+                    const Zstringc& conflictMsg = getConflictAmbiguousItemName(itCase->ref->first);
                     std::for_each(itCase, itEndCase, [&](const FileRef& fr)
                     {
                         if (fr.leftSide)
@@ -800,16 +800,16 @@ void matchFolders(const MapType& mapLeft, const MapType& mapRight, ProcessLeftOn
 }
 
 
-void MergeSides::mergeTwoSides(const FolderContainer& lhs, const FolderContainer& rhs, const Zstringw* errorMsg, ContainerObject& output)
+void MergeSides::mergeTwoSides(const FolderContainer& lhs, const FolderContainer& rhs, const Zstringc* errorMsg, ContainerObject& output)
 {
     using FileData = FolderContainer::FileList::value_type;
 
-    matchFolders(lhs.files, rhs.files, [&](const FileData& fileLeft, const Zstringw* conflictMsg)
+    matchFolders(lhs.files, rhs.files, [&](const FileData& fileLeft, const Zstringc* conflictMsg)
     {
         FilePair& newItem = output.addSubFile< LEFT_SIDE>(fileLeft .first, fileLeft .second);
         checkFailedRead(newItem, conflictMsg ? conflictMsg : errorMsg);
     },
-    [&](const FileData& fileRight, const Zstringw* conflictMsg)
+    [&](const FileData& fileRight, const Zstringc* conflictMsg)
     {
         FilePair& newItem = output.addSubFile<RIGHT_SIDE>(fileRight.first, fileRight.second);
         checkFailedRead(newItem, conflictMsg ? conflictMsg : errorMsg);
@@ -829,12 +829,12 @@ void MergeSides::mergeTwoSides(const FolderContainer& lhs, const FolderContainer
     //-----------------------------------------------------------------------------------------------
     using SymlinkData = FolderContainer::SymlinkList::value_type;
 
-    matchFolders(lhs.symlinks, rhs.symlinks, [&](const SymlinkData& symlinkLeft, const Zstringw* conflictMsg)
+    matchFolders(lhs.symlinks, rhs.symlinks, [&](const SymlinkData& symlinkLeft, const Zstringc* conflictMsg)
     {
         SymlinkPair& newItem = output.addSubLink< LEFT_SIDE>(symlinkLeft .first, symlinkLeft .second);
         checkFailedRead(newItem, conflictMsg ? conflictMsg : errorMsg);
     },
-    [&](const SymlinkData& symlinkRight, const Zstringw* conflictMsg)
+    [&](const SymlinkData& symlinkRight, const Zstringc* conflictMsg)
     {
         SymlinkPair& newItem = output.addSubLink<RIGHT_SIDE>(symlinkRight.first, symlinkRight.second);
         checkFailedRead(newItem, conflictMsg ? conflictMsg : errorMsg);
@@ -853,22 +853,22 @@ void MergeSides::mergeTwoSides(const FolderContainer& lhs, const FolderContainer
     //-----------------------------------------------------------------------------------------------
     using FolderData = FolderContainer::FolderList::value_type;
 
-    matchFolders(lhs.folders, rhs.folders, [&](const FolderData& dirLeft, const Zstringw* conflictMsg)
+    matchFolders(lhs.folders, rhs.folders, [&](const FolderData& dirLeft, const Zstringc* conflictMsg)
     {
         FolderPair& newFolder = output.addSubFolder<LEFT_SIDE>(dirLeft.first, dirLeft.second.first);
-        const Zstringw* errorMsgNew = checkFailedRead(newFolder, conflictMsg ? conflictMsg : errorMsg);
+        const Zstringc* errorMsgNew = checkFailedRead(newFolder, conflictMsg ? conflictMsg : errorMsg);
         this->fillOneSide<LEFT_SIDE>(dirLeft.second.second, errorMsgNew, newFolder); //recurse
     },
-    [&](const FolderData& dirRight, const Zstringw* conflictMsg)
+    [&](const FolderData& dirRight, const Zstringc* conflictMsg)
     {
         FolderPair& newFolder = output.addSubFolder<RIGHT_SIDE>(dirRight.first, dirRight.second.first);
-        const Zstringw* errorMsgNew = checkFailedRead(newFolder, conflictMsg ? conflictMsg : errorMsg);
+        const Zstringc* errorMsgNew = checkFailedRead(newFolder, conflictMsg ? conflictMsg : errorMsg);
         this->fillOneSide<RIGHT_SIDE>(dirRight.second.second, errorMsgNew, newFolder); //recurse
     },
     [&](const FolderData& dirLeft, const FolderData& dirRight)
     {
         FolderPair& newFolder = output.addSubFolder(dirLeft.first, dirLeft.second.first, DIR_EQUAL, dirRight.first, dirRight.second.first);
-        const Zstringw* errorMsgNew = checkFailedRead(newFolder, errorMsg);
+        const Zstringc* errorMsgNew = checkFailedRead(newFolder, errorMsg);
 
         if (!errorMsgNew)
             if (getUnicodeNormalForm(dirLeft.first) !=
@@ -925,12 +925,12 @@ std::shared_ptr<BaseFolderPair> ComparisonBuffer::performComparison(const Resolv
     const DirectoryValue* bufValueLeft  = getDirValue(fp.folderPathLeft);
     const DirectoryValue* bufValueRight = getDirValue(fp.folderPathRight);
 
-    std::map<ZstringNoCase, Zstringw> failedReads; //base-relative paths or empty if read-error for whole base directory
+    std::map<ZstringNoCase, Zstringc> failedReads; //base-relative paths or empty if read-error for whole base directory
     {
-        auto append = [&](const std::map<Zstring, std::wstring>& c)
+        auto append = [&](const std::map<Zstring, Zstringc>& c)
         {
             for (const auto& [relPath, errorMsg] : c)
-                failedReads.emplace(relPath, copyStringTo<Zstringw>(errorMsg));
+                failedReads.emplace(relPath, errorMsg);
         };
 
         //mix failedFolderReads with failedItemReads:
@@ -948,7 +948,7 @@ std::shared_ptr<BaseFolderPair> ComparisonBuffer::performComparison(const Resolv
         excludefilterFailedRead += Zstr("*\n");
     else
         for (const auto& [relPath, errorMsg] : failedReads)
-            excludefilterFailedRead += relPath.upperCase + Zstr("\n"); //exclude item AND (potential) child items!
+            excludefilterFailedRead += relPath.upperCase + Zstr('\n'); //exclude item AND (potential) child items!
 
     //somewhat obscure, but it's possible on Linux file systems to have a backslash as part of a file name
     //=> avoid misinterpretation when parsing the filter phrase in PathFilter (see path_filter.cpp::addFilterEntry())
@@ -986,37 +986,6 @@ std::shared_ptr<BaseFolderPair> ComparisonBuffer::performComparison(const Resolv
 }
 
 
-void fff::logNonDefaultSettings(const XmlGlobalSettings& activeSettings, PhaseCallback& callback)
-{
-    const XmlGlobalSettings defaultSettings;
-    std::wstring changedSettingsMsg;
-
-    if (activeSettings.failSafeFileCopy != defaultSettings.failSafeFileCopy)
-        changedSettingsMsg += L"\n    " + _("Fail-safe file copy") + L" - " + (activeSettings.failSafeFileCopy ? _("Enabled") : _("Disabled"));
-
-    if (activeSettings.copyLockedFiles != defaultSettings.copyLockedFiles)
-        changedSettingsMsg += L"\n    " + _("Copy locked files") + L" - " + (activeSettings.copyLockedFiles ? _("Enabled") : _("Disabled"));
-
-    if (activeSettings.copyFilePermissions != defaultSettings.copyFilePermissions)
-        changedSettingsMsg += L"\n    " + _("Copy file access permissions") + L" - " + (activeSettings.copyFilePermissions ? _("Enabled") : _("Disabled"));
-
-    if (activeSettings.fileTimeTolerance != defaultSettings.fileTimeTolerance)
-        changedSettingsMsg += L"\n    " + _("File time tolerance") + L" - " + numberTo<std::wstring>(activeSettings.fileTimeTolerance);
-
-    if (activeSettings.runWithBackgroundPriority != defaultSettings.runWithBackgroundPriority)
-        changedSettingsMsg += L"\n    " + _("Run with background priority") + L" - " + (activeSettings.runWithBackgroundPriority ? _("Enabled") : _("Disabled"));
-
-    if (activeSettings.createLockFile != defaultSettings.createLockFile)
-        changedSettingsMsg += L"\n    " + _("Lock directories during sync") + L" - " + (activeSettings.createLockFile ? _("Enabled") : _("Disabled"));
-
-    if (activeSettings.verifyFileCopy != defaultSettings.verifyFileCopy)
-        changedSettingsMsg += L"\n    " + _("Verify copied files") + L" - " + (activeSettings.verifyFileCopy ? _("Enabled") : _("Disabled"));
-
-    if (!changedSettingsMsg.empty())
-        callback.reportInfo(_("Using non-default global settings:") + changedSettingsMsg); //throw X
-}
-
-
 FolderComparison fff::compare(WarningDialogs& warnings,
                               int fileTimeTolerance,
                               bool allowUserInteraction,
@@ -1062,7 +1031,7 @@ FolderComparison fff::compare(WarningDialogs& warnings,
                                                                allowUserInteraction, warnings, callback); //throw X
     //directory existence only checked *once* to avoid race conditions!
     if (resInfo.resolvedPairs.size() != fpCfgList.size())
-        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
 
     auto basefolderExisting = [&](const AbstractPath& folderPath) { return contains(resInfo.existingBaseFolders, folderPath); };
 
@@ -1099,14 +1068,14 @@ FolderComparison fff::compare(WarningDialogs& warnings,
                                                                      folderPair.folderPathRight, fpCfg.filter.nameFilter.ref()))
             {
                 msg += L"\n\n" +
-                       AFS::getDisplayPath(folderPair.folderPathLeft) + L"\n" +
+                       AFS::getDisplayPath(folderPair.folderPathLeft) + L'\n' +
                        AFS::getDisplayPath(folderPair.folderPathRight);
                 if (!pd->relPath.empty())
-                    msg += L"\n" + _("Exclude:") + L" " + utfTo<std::wstring>(FILE_NAME_SEPARATOR + pd->relPath + FILE_NAME_SEPARATOR);
+                    msg += L'\n' + _("Exclude:") + L' ' + utfTo<std::wstring>(FILE_NAME_SEPARATOR + pd->relPath + FILE_NAME_SEPARATOR);
             }
 
         if (!msg.empty())
-            callback.reportWarning(_("One base folder of a folder pair is contained in the other one.") + L"\n" + //throw X
+            callback.reportWarning(_("One base folder of a folder pair is contained in the other one.") + L'\n' + //throw X
                                    _("The folder should be excluded from synchronization via filter.") + msg, warnings.warnDependentFolderPair);
     }
     //-------------------end of basic checks------------------------------------------
@@ -1187,7 +1156,7 @@ FolderComparison fff::compare(WarningDialogs& warnings,
     }
     catch (const std::bad_alloc& e)
     {
-        callback.reportFatalError(_("Out of memory.") + L" " + utfTo<std::wstring>(e.what()));
+        callback.reportFatalError(_("Out of memory.") + L' ' + utfTo<std::wstring>(e.what()));
         return {};
     }
 }
diff --git a/FreeFileSync/Source/base/comparison.h b/FreeFileSync/Source/base/comparison.h
index b3315926..d547ee05 100644
--- a/FreeFileSync/Source/base/comparison.h
+++ b/FreeFileSync/Source/base/comparison.h
@@ -7,7 +7,7 @@
 #ifndef COMPARISON_H_8032178534545426
 #define COMPARISON_H_8032178534545426
 
-#include "config.h"
+//#include "config.h"
 #include "file_hierarchy.h"
 #include "process_callback.h"
 #include "norm_filter.h"
@@ -47,9 +47,6 @@ struct FolderPairCfg
 
 std::vector<FolderPairCfg> extractCompareCfg(const MainConfiguration& mainCfg); //fill FolderPairCfg and resolve folder pairs
 
-//inform about (important) non-default global settings related to comparison and synchronization
-void logNonDefaultSettings(const XmlGlobalSettings& currentSettings, PhaseCallback& callback);
-
 //FFS core routine:     output.size() == fpCfgList.size() or 0 on fatal error
 FolderComparison compare(WarningDialogs& warnings,
                          int fileTimeTolerance,
diff --git a/FreeFileSync/Source/base/db_file.cpp b/FreeFileSync/Source/base/db_file.cpp
index 94a6afc4..23e42776 100644
--- a/FreeFileSync/Source/base/db_file.cpp
+++ b/FreeFileSync/Source/base/db_file.cpp
@@ -30,7 +30,7 @@ DEFINE_NEW_FILE_ERROR(FileErrorDatabaseNotExisting)
 struct SessionData
 {
     bool isLeadStream = false;
-    ByteArray rawStream;
+    std::string rawStream;
 };
 bool operator==(const SessionData& lhs, const SessionData& rhs) { return lhs.isLeadStream == rhs.isLeadStream && lhs.rawStream == rhs.rawStream; }
 
@@ -77,8 +77,8 @@ void saveStreams(const DbStreams& streamList, const AbstractPath& dbPath, const
     {
         writeContainer<std::string>(memStreamOut, sessionID);
 
-        writeNumber   <int8_t   >(memStreamOut, sessionData.isLeadStream);
-        writeContainer<ByteArray>(memStreamOut, sessionData.rawStream);
+        writeNumber<int8_t>(memStreamOut, sessionData.isLeadStream);
+        writeContainer     (memStreamOut, sessionData.rawStream);
     }
 
     writeNumber<uint32_t>(memStreamOut, getCrc32(memStreamOut.ref()));
@@ -139,10 +139,10 @@ DbStreams loadStreams(const AbstractPath& dbPath, const IOCallback& notifyUnbuff
         {
             assert(byteStream.size() >= sizeof(uint32_t)); //obviously in this context!
             MemoryStreamOut<std::string> crcStreamOut;
-            writeNumber<uint32_t>(crcStreamOut, getCrc32({ byteStream.begin(), byteStream.end() - sizeof(uint32_t) }));
+            writeNumber<uint32_t>(crcStreamOut, getCrc32(byteStream.begin(), byteStream.end() - sizeof(uint32_t)));
 
             if (!endsWith(byteStream, crcStreamOut.ref()))
-                throw FileError(_("Database file is corrupted:") + L" " + fmtPath(AFS::getDisplayPath(dbPath)), L"Invalid checksum.");
+                throw FileError(_("Database file is corrupted:") + L' ' + fmtPath(AFS::getDisplayPath(dbPath)), L"Invalid checksum.");
         }
 
         DbStreams output;
@@ -157,7 +157,7 @@ DbStreams loadStreams(const AbstractPath& dbPath, const IOCallback& notifyUnbuff
 
             if (version == 9) //TODO: remove migration code at some time! v9 used until 2017-02-01
             {
-                sessionData.rawStream = readContainer<ByteArray>(memStreamIn); //throw UnexpectedEndOfStreamError
+                sessionData.rawStream = readContainer<std::string>(memStreamIn); //throw UnexpectedEndOfStreamError
 
                 MemoryStreamIn streamIn(sessionData.rawStream);
                 const int streamVersion = readNumber<int32_t>(streamIn); //throw UnexpectedEndOfStreamError
@@ -167,8 +167,8 @@ DbStreams loadStreams(const AbstractPath& dbPath, const IOCallback& notifyUnbuff
             }
             else
             {
-                sessionData.isLeadStream = readNumber   <int8_t   >(memStreamIn) != 0; //throw UnexpectedEndOfStreamError
-                sessionData.rawStream    = readContainer<ByteArray>(memStreamIn);      //
+                sessionData.isLeadStream = readNumber   <int8_t     >(memStreamIn) != 0; //throw UnexpectedEndOfStreamError
+                sessionData.rawStream    = readContainer<std::string>(memStreamIn);      //
             }
 
             output[sessionID] = std::move(sessionData);
@@ -177,7 +177,7 @@ DbStreams loadStreams(const AbstractPath& dbPath, const IOCallback& notifyUnbuff
     }
     catch (UnexpectedEndOfStreamError&)
     {
-        throw FileError(_("Database file is corrupted:") + L" " + fmtPath(AFS::getDisplayPath(dbPath)), L"Unexpected end of stream.");
+        throw FileError(_("Database file is corrupted:") + L' ' + fmtPath(AFS::getDisplayPath(dbPath)), L"Unexpected end of stream.");
     }
 }
 
@@ -189,16 +189,16 @@ public:
     static void execute(const InSyncFolder& dbFolder, //throw FileError
                         const std::wstring& displayFilePathL, //used for diagnostics only
                         const std::wstring& displayFilePathR,
-                        ByteArray& streamL,
-                        ByteArray& streamR)
+                        std::string& streamL,
+                        std::string& streamR)
     {
-        MemoryStreamOut<ByteArray> outL;
-        MemoryStreamOut<ByteArray> outR;
+        MemoryStreamOut<std::string> outL;
+        MemoryStreamOut<std::string> outR;
         //save format version
         writeNumber<int32_t>(outL, DB_STREAM_VERSION);
         writeNumber<int32_t>(outR, DB_STREAM_VERSION);
 
-        auto compStream = [&](const ByteArray& stream) -> ByteArray //throw FileError
+        auto compStream = [&](const std::string& stream) //throw FileError
         {
             try
             {
@@ -227,16 +227,16 @@ public:
         generator.recurse(dbFolder);
         //PERF_STOP
 
-        const ByteArray bufText     = compStream(generator.streamOutText_    .ref());
-        const ByteArray bufSmallNum = compStream(generator.streamOutSmallNum_.ref());
-        const ByteArray bufBigNum   = compStream(generator.streamOutBigNum_  .ref());
+        const std::string bufText     = compStream(generator.streamOutText_    .ref());
+        const std::string bufSmallNum = compStream(generator.streamOutSmallNum_.ref());
+        const std::string bufBigNum   = compStream(generator.streamOutBigNum_  .ref());
 
-        MemoryStreamOut<ByteArray> streamOut;
+        MemoryStreamOut<std::string> streamOut;
         writeContainer(streamOut, bufText);
         writeContainer(streamOut, bufSmallNum);
         writeContainer(streamOut, bufBigNum);
 
-        const ByteArray& buf = streamOut.ref();
+        const std::string& buf = streamOut.ref();
 
         //distribute "outputBoth" over left and right streams:
         const size_t size1stPart = buf.size() / 2;
@@ -245,11 +245,11 @@ public:
         writeNumber<uint64_t>(outL, size1stPart);
         writeNumber<uint64_t>(outR, size2ndPart);
 
-        if (size1stPart > 0) writeArray(outL, &*buf.begin(), size1stPart);
-        if (size2ndPart > 0) writeArray(outR, &*buf.begin() + size1stPart, size2ndPart);
+        if (size1stPart > 0) writeArray(outL, &buf[0], size1stPart);
+        if (size2ndPart > 0) writeArray(outR, &buf[0] + size1stPart, size2ndPart);
 
-        streamL = outL.ref();
-        streamR = outR.ref();
+        streamL = std::move(outL.ref());
+        streamR = std::move(outR.ref());
     }
 
 private:
@@ -286,25 +286,25 @@ private:
         }
     }
 
-    static void writeUtf8(MemoryStreamOut<ByteArray>& streamOut, const Zstring& str) { writeContainer(streamOut, utfTo<Zbase<char>>(str)); }
+    static void writeUtf8(MemoryStreamOut<std::string>& streamOut, const Zstring& str) { writeContainer(streamOut, utfTo<std::string>(str)); }
 
-    static void writeFileDescr(MemoryStreamOut<ByteArray>& streamOut, const InSyncDescrFile& descr)
+    static void writeFileDescr(MemoryStreamOut<std::string>& streamOut, const InSyncDescrFile& descr)
     {
         writeNumber<int64_t>(streamOut, descr.modTime);
         writeContainer(streamOut, descr.fileId);
-        static_assert(std::is_same_v<decltype(descr.fileId), Zbase<char>>);
+        static_assert(std::is_same_v<decltype(descr.fileId), std::string>);
     }
 
-    static void writeLinkDescr(MemoryStreamOut<ByteArray>& streamOut, const InSyncDescrLink& descr)
+    static void writeLinkDescr(MemoryStreamOut<std::string>& streamOut, const InSyncDescrLink& descr)
     {
         writeNumber<int64_t>(streamOut, descr.modTime);
     }
 
     //maximize zlib compression by grouping similar data (=> 20% size reduction!)
     // -> further ~5% reduction possible by having one container per data type
-    MemoryStreamOut<ByteArray> streamOutText_;     //
-    MemoryStreamOut<ByteArray> streamOutSmallNum_; //data with bias to lead side (= always left in this context)
-    MemoryStreamOut<ByteArray> streamOutBigNum_;   //
+    MemoryStreamOut<std::string> streamOutText_;     //
+    MemoryStreamOut<std::string> streamOutSmallNum_; //data with bias to lead side (= always left in this context)
+    MemoryStreamOut<std::string> streamOutBigNum_;   //
 };
 
 
@@ -312,12 +312,12 @@ class StreamParser
 {
 public:
     static SharedRef<InSyncFolder> execute(bool leadStreamLeft, //throw FileError
-                                           const ByteArray& streamL,
-                                           const ByteArray& streamR,
+                                           const std::string& streamL,
+                                           const std::string& streamR,
                                            const std::wstring& displayFilePathL, //for diagnostics only
                                            const std::wstring& displayFilePathR)
     {
-        auto decompStream = [&](const ByteArray& stream) -> ByteArray //throw FileError
+        auto decompStream = [&](const std::string& stream) //throw FileError
         {
             try
             {
@@ -338,7 +338,7 @@ public:
             const int streamVersionR = readNumber<int32_t>(streamInR); //
 
             if (streamVersion != streamVersionR)
-                throw FileError(_("Database file is corrupted:") + L"\n" + fmtPath(displayFilePathL) + L"\n" + fmtPath(displayFilePathR), L"Different stream formats");
+                throw FileError(_("Database file is corrupted:") + L'\n' + fmtPath(displayFilePathL) + L'\n' + fmtPath(displayFilePathR), L"Different stream formats");
 
             //TODO: remove migration code at some time! 2017-02-01
             if (streamVersion != 2 &&
@@ -352,23 +352,22 @@ public:
                 const bool has1stPartR = readNumber<int8_t>(streamInR) != 0; //
 
                 if (has1stPartL == has1stPartR)
-                    throw FileError(_("Database file is corrupted:") + L"\n" + fmtPath(displayFilePathL) + L"\n" + fmtPath(displayFilePathR), L"Second stream part missing");
+                    throw FileError(_("Database file is corrupted:") + L'\n' + fmtPath(displayFilePathL) + L'\n' + fmtPath(displayFilePathR), L"Second stream part missing");
                 if (has1stPartL != leadStreamLeft)
-                    throw FileError(_("Database file is corrupted:") + L"\n" + fmtPath(displayFilePathL) + L"\n" + fmtPath(displayFilePathR), L"has1stPartL != leadStreamLeft");
+                    throw FileError(_("Database file is corrupted:") + L'\n' + fmtPath(displayFilePathL) + L'\n' + fmtPath(displayFilePathR), L"has1stPartL != leadStreamLeft");
 
-                MemoryStreamIn<ByteArray>& in1stPart = leadStreamLeft ? streamInL : streamInR;
-                MemoryStreamIn<ByteArray>& in2ndPart = leadStreamLeft ? streamInR : streamInL;
+                MemoryStreamIn<std::string>& in1stPart = leadStreamLeft ? streamInL : streamInR;
+                MemoryStreamIn<std::string>& in2ndPart = leadStreamLeft ? streamInR : streamInL;
 
                 const size_t size1stPart = static_cast<size_t>(readNumber<uint64_t>(in1stPart));
                 const size_t size2ndPart = static_cast<size_t>(readNumber<uint64_t>(in2ndPart));
 
-                ByteArray tmpB;
-                tmpB.resize(size1stPart + size2ndPart); //throw std::bad_alloc
-                readArray(in1stPart, &*tmpB.begin(),               size1stPart); //stream always non-empty
-                readArray(in2ndPart, &*tmpB.begin() + size1stPart, size2ndPart); //throw UnexpectedEndOfStreamError
+                std::string tmpB(size1stPart + size2ndPart, '\0'); //throw std::bad_alloc
+                readArray(in1stPart, &tmpB[0],               size1stPart); //stream always non-empty
+                readArray(in2ndPart, &tmpB[0] + size1stPart, size2ndPart); //throw UnexpectedEndOfStreamError
 
-                const ByteArray tmpL = readContainer<ByteArray>(streamInL);
-                const ByteArray tmpR = readContainer<ByteArray>(streamInR);
+                const std::string tmpL = readContainer<std::string>(streamInL);
+                const std::string tmpR = readContainer<std::string>(streamInR);
 
                 auto output = makeSharedRef<InSyncFolder>(InSyncFolder::DIR_STATUS_IN_SYNC);
                 StreamParserV2 parser(decompStream(tmpL),
@@ -379,22 +378,20 @@ public:
             }
             else
             {
-                MemoryStreamIn<ByteArray>& streamInPart1 = leadStreamLeft ? streamInL : streamInR;
-                MemoryStreamIn<ByteArray>& streamInPart2 = leadStreamLeft ? streamInR : streamInL;
+                MemoryStreamIn<std::string>& streamInPart1 = leadStreamLeft ? streamInL : streamInR;
+                MemoryStreamIn<std::string>& streamInPart2 = leadStreamLeft ? streamInR : streamInL;
 
                 const size_t sizePart1 = static_cast<size_t>(readNumber<uint64_t>(streamInPart1));
                 const size_t sizePart2 = static_cast<size_t>(readNumber<uint64_t>(streamInPart2));
 
-                ByteArray buf;
-                buf.resize(sizePart1 + sizePart2); //throw std::bad_alloc
-
-                if (sizePart1 > 0) readArray(streamInPart1, &*buf.begin(),             sizePart1); //throw UnexpectedEndOfStreamError
-                if (sizePart2 > 0) readArray(streamInPart2, &*buf.begin() + sizePart1, sizePart2); //
+                std::string buf(sizePart1 + sizePart2, '\0');
+                if (sizePart1 > 0) readArray(streamInPart1, &buf[0],             sizePart1); //throw UnexpectedEndOfStreamError
+                if (sizePart2 > 0) readArray(streamInPart2, &buf[0] + sizePart1, sizePart2); //
 
                 MemoryStreamIn streamIn(buf);
-                const ByteArray bufText     = readContainer<ByteArray>(streamIn); //
-                const ByteArray bufSmallNum = readContainer<ByteArray>(streamIn); //throw UnexpectedEndOfStreamError
-                const ByteArray bufBigNum   = readContainer<ByteArray>(streamIn); //
+                const std::string bufText     = readContainer<std::string>(streamIn); //
+                const std::string bufSmallNum = readContainer<std::string>(streamIn); //throw UnexpectedEndOfStreamError
+                const std::string bufBigNum   = readContainer<std::string>(streamIn); //
 
                 auto output = makeSharedRef<InSyncFolder>(InSyncFolder::DIR_STATUS_IN_SYNC);
                 StreamParser parser(streamVersion,
@@ -410,12 +407,12 @@ public:
         }
         catch (UnexpectedEndOfStreamError&)
         {
-            throw FileError(_("Database file is corrupted:") + L"\n" + fmtPath(displayFilePathL) + L"\n" + fmtPath(displayFilePathR), L"Unexpected end of stream.");
+            throw FileError(_("Database file is corrupted:") + L'\n' + fmtPath(displayFilePathL) + L'\n' + fmtPath(displayFilePathR), L"Unexpected end of stream.");
         }
     }
 
 private:
-    StreamParser(int streamVersion, const ByteArray& bufText, const ByteArray& bufSmallNumbers, const ByteArray& bufBigNumbers) :
+    StreamParser(int streamVersion, const std::string& bufText, const std::string& bufSmallNumbers, const std::string& bufBigNumbers) :
         streamVersion_(streamVersion),
         streamInText_(bufText),
         streamInSmallNum_(bufSmallNumbers),
@@ -467,20 +464,20 @@ private:
         }
     }
 
-    static Zstring readUtf8(MemoryStreamIn<ByteArray>& streamIn) { return utfTo<Zstring>(readContainer<Zbase<char>>(streamIn)); } //throw UnexpectedEndOfStreamError
+    static Zstring readUtf8(MemoryStreamIn<std::string>& streamIn) { return utfTo<Zstring>(readContainer<std::string>(streamIn)); } //throw UnexpectedEndOfStreamError
     //optional: use null-termination: 5% overall size reduction
     //optional: split into streamInText_/streamInSmallNum_: overall size increase! (why?)
 
-    static InSyncDescrFile readFileDescr(MemoryStreamIn<ByteArray>& streamIn) //throw UnexpectedEndOfStreamError
+    static InSyncDescrFile readFileDescr(MemoryStreamIn<std::string>& streamIn) //throw UnexpectedEndOfStreamError
     {
         //attention: order of function argument evaluation is undefined! So do it one after the other...
         const auto modTime = readNumber<int64_t>(streamIn); //throw UnexpectedEndOfStreamError
-        const AFS::FileId fileId = readContainer<Zbase<char>>(streamIn);
+        const auto fileId = readContainer<AFS::FileId>(streamIn);
 
         return InSyncDescrFile(modTime, fileId);
     }
 
-    static InSyncDescrLink readLinkDescr(MemoryStreamIn<ByteArray>& streamIn) //throw UnexpectedEndOfStreamError
+    static InSyncDescrLink readLinkDescr(MemoryStreamIn<std::string>& streamIn) //throw UnexpectedEndOfStreamError
     {
         const auto modTime = readNumber<int64_t>(streamIn);
         return InSyncDescrLink(modTime);
@@ -490,9 +487,9 @@ private:
     class StreamParserV2
     {
     public:
-        StreamParserV2(const ByteArray& bufferL,
-                       const ByteArray& bufferR,
-                       const ByteArray& bufferB) :
+        StreamParserV2(const std::string& bufferL,
+                       const std::string& bufferR,
+                       const std::string& bufferB) :
             inputLeft_ (bufferL),
             inputRight_(bufferR),
             inputBoth_ (bufferB) {}
@@ -532,15 +529,15 @@ private:
         }
 
     private:
-        MemoryStreamIn<ByteArray> inputLeft_;  //data related to one side only
-        MemoryStreamIn<ByteArray> inputRight_; //
-        MemoryStreamIn<ByteArray> inputBoth_;  //data concerning both sides
+        MemoryStreamIn<std::string> inputLeft_;  //data related to one side only
+        MemoryStreamIn<std::string> inputRight_; //
+        MemoryStreamIn<std::string> inputBoth_;  //data concerning both sides
     };
 
     const int streamVersion_;
-    MemoryStreamIn<ByteArray> streamInText_;     //
-    MemoryStreamIn<ByteArray> streamInSmallNum_; //data with bias to lead side
-    MemoryStreamIn<ByteArray> streamInBigNum_;   //
+    MemoryStreamIn<std::string> streamInText_;     //
+    MemoryStreamIn<std::string> streamInSmallNum_; //data with bias to lead side
+    MemoryStreamIn<std::string> streamInBigNum_;   //
 };
 
 //#######################################################################################################################################
@@ -757,7 +754,7 @@ std::pair<DbStreams::const_iterator,
             if (itL->second.isLeadStream != itR->second.isLeadStream)
             {
                 if (itCommonL != streamsLeft.end()) //should not be possible!
-                    throw FileError(_("Database file is corrupted:") + L"\n" + fmtPath(displayFilePathL) + L"\n" + fmtPath(displayFilePathR),
+                    throw FileError(_("Database file is corrupted:") + L'\n' + fmtPath(displayFilePathL) + L'\n' + fmtPath(displayFilePathR),
                                     L"Multiple common sessions found.");
                 itCommonL = itL;
                 itCommonR = itR;
diff --git a/FreeFileSync/Source/base/dir_exist_async.h b/FreeFileSync/Source/base/dir_exist_async.h
index 74572919..ff431902 100644
--- a/FreeFileSync/Source/base/dir_exist_async.h
+++ b/FreeFileSync/Source/base/dir_exist_async.h
@@ -103,7 +103,7 @@ FolderStatus getFolderStatusNonBlocking(const std::set<AbstractPath>& folderPath
 
         if (!isReady(future))
             output.failedChecks.emplace(folderPath, FileError(replaceCpy(_("Timeout while searching for folder %x."), L"%x", displayPathFmt) +
-                                                              L" [" + _P("1 sec", "%x sec", deviceTimeOutSec) + L"]"));
+                                                              L" [" + _P("1 sec", "%x sec", deviceTimeOutSec) + L']'));
         else
             try
             {
diff --git a/FreeFileSync/Source/base/dir_lock.cpp b/FreeFileSync/Source/base/dir_lock.cpp
index ab76158f..5ba444c7 100644
--- a/FreeFileSync/Source/base/dir_lock.cpp
+++ b/FreeFileSync/Source/base/dir_lock.cpp
@@ -149,7 +149,7 @@ LockInformation getLockInfoFromCurrentProcess() //throw FileError
     std::vector<char> buffer(10000);
     if (::gethostname(&buffer[0], buffer.size()) != 0)
         THROW_LAST_FILE_ERROR(_("Cannot get process information."), L"gethostname");
-    lockInfo.computerName = osName + " " + &buffer[0] + ".";
+    lockInfo.computerName = osName + ' ' + &buffer[0] + '.';
 
     if (::getdomainname(&buffer[0], buffer.size()) != 0)
         THROW_LAST_FILE_ERROR(_("Cannot get process information."), L"getdomainname");
@@ -182,7 +182,7 @@ std::string serialize(const LockInformation& lockInfo)
     writeNumber<uint64_t>(streamOut, lockInfo.processId);
 
     writeNumber<uint32_t>(streamOut, getCrc32(streamOut.ref()));
-    writeArray(streamOut, "x", 1); //sentinel: mark logical end with a non-whitespace character
+    writeArray(streamOut, "x", 1); //sentinel: mark logical end with a non-space character
     return streamOut.ref();
 }
 
@@ -206,12 +206,14 @@ LockInformation unserialize(const std::string& byteStream) //throw UnexpectedEnd
         ;
     else //catch data corruption ASAP + don't rely on std::bad_alloc for consistency checking
     {
-        std::string byteStreamTrm = trimCpy(byteStream, false, true); //get rid of space chars
-        assert(byteStreamTrm.size() >= sizeof(uint32_t) + sizeof('x')); //obviously in this context!
-        byteStreamTrm.pop_back();
+        const size_t posEnd = byteStream.rfind('x'); //skip blanks (+ unrelated corrupted data e.g. nulls!)
+        if (posEnd == std::string::npos)
+            throw UnexpectedEndOfStreamError(); //well, not really...!?
+
+        const std::string_view byteStreamTrm = makeStringView(byteStream.begin(), posEnd);
 
         MemoryStreamOut<std::string> crcStreamOut;
-        writeNumber<uint32_t>(crcStreamOut, getCrc32({ byteStreamTrm.begin(), byteStreamTrm.end() - sizeof(uint32_t) }));
+        writeNumber<uint32_t>(crcStreamOut, getCrc32(byteStreamTrm.begin(), byteStreamTrm.end() - sizeof(uint32_t)));
 
         if (!endsWith(byteStreamTrm, crcStreamOut.ref()))
             throw UnexpectedEndOfStreamError(); //well, not really...!?
diff --git a/FreeFileSync/Source/base/file_hierarchy.cpp b/FreeFileSync/Source/base/file_hierarchy.cpp
index 1f10a793..debaa031 100644
--- a/FreeFileSync/Source/base/file_hierarchy.cpp
+++ b/FreeFileSync/Source/base/file_hierarchy.cpp
@@ -359,7 +359,7 @@ const wchar_t arrowRight[] = L"->";
 
 std::wstring fff::getCategoryDescription(const FileSystemObject& fsObj)
 {
-    const std::wstring footer = L"\n[" + utfTo<std::wstring>(fsObj. getItemNameAny()) + L"]";
+    const std::wstring footer = L"\n[" + utfTo<std::wstring>(fsObj. getItemNameAny()) + L']';
 
     const CompareFileResult cmpRes = fsObj.getCategory();
     switch (cmpRes)
@@ -379,21 +379,21 @@ std::wstring fff::getCategoryDescription(const FileSystemObject& fsObj)
             [&](const FilePair& file)
             {
                 descr += std::wstring(L"\n") +
-                         arrowLeft  + L" " + formatUtcToLocalTime(file.getLastWriteTime< LEFT_SIDE>()) + L"\n" +
-                         arrowRight + L" " + formatUtcToLocalTime(file.getLastWriteTime<RIGHT_SIDE>());
+                         arrowLeft  + L' ' + formatUtcToLocalTime(file.getLastWriteTime< LEFT_SIDE>()) + L'\n' +
+                         arrowRight + L' ' + formatUtcToLocalTime(file.getLastWriteTime<RIGHT_SIDE>());
             },
             [&](const SymlinkPair& symlink)
             {
                 descr += std::wstring(L"\n") +
-                         arrowLeft  + L" " + formatUtcToLocalTime(symlink.getLastWriteTime< LEFT_SIDE>()) + L"\n" +
-                         arrowRight + L" " + formatUtcToLocalTime(symlink.getLastWriteTime<RIGHT_SIDE>());
+                         arrowLeft  + L' ' + formatUtcToLocalTime(symlink.getLastWriteTime< LEFT_SIDE>()) + L'\n' +
+                         arrowRight + L' ' + formatUtcToLocalTime(symlink.getLastWriteTime<RIGHT_SIDE>());
             });
             return descr + footer;
         }
 
         case FILE_DIFFERENT_METADATA:
         case FILE_CONFLICT:
-            return fsObj.getCatExtraDescription() + footer;
+            return utfTo<std::wstring>(fsObj.getCatExtraDescription()) + footer;
     }
     assert(false);
     return std::wstring();
@@ -440,7 +440,7 @@ std::wstring fff::getSyncOpDescription(SyncOperation op)
 
 std::wstring fff::getSyncOpDescription(const FileSystemObject& fsObj)
 {
-    const std::wstring footer = L"\n[" + utfTo<std::wstring>(fsObj. getItemNameAny()) + L"]";
+    const std::wstring footer = L"\n[" + utfTo<std::wstring>(fsObj. getItemNameAny()) + L']';
 
     const SyncOperation op = fsObj.getSyncOperation();
     switch (op)
@@ -466,8 +466,8 @@ std::wstring fff::getSyncOpDescription(const FileSystemObject& fsObj)
 
             if (getUnicodeNormalForm(itemNameOld) !=
                 getUnicodeNormalForm(itemNameNew)) //detected change in case
-                return getSyncOpDescription(op) + L"\n" +
-                       fmtPath(itemNameOld) + L" " + arrowRight + L"\n" + //show short name only
+                return getSyncOpDescription(op) + L'\n' +
+                       fmtPath(itemNameOld) + L' ' + arrowRight + L'\n' + //show short name only
                        fmtPath(itemNameNew) /*+ footer -> redundant */;
         }
         return getSyncOpDescription(op) + footer; //fallback
@@ -492,14 +492,14 @@ std::wstring fff::getSyncOpDescription(const FileSystemObject& fsObj)
                     const Zstring relPathTo   = getRelName(*fileTo,   onLeft);
 
                     //attention: ::SetWindowText() doesn't handle tab characters correctly in combination with certain file names, so don't use them
-                    return getSyncOpDescription(op) + L"\n" +
+                    return getSyncOpDescription(op) + L'\n' +
                            (beforeLast(relPathFrom, FILE_NAME_SEPARATOR, IF_MISSING_RETURN_NONE) ==
                             beforeLast(relPathTo,   FILE_NAME_SEPARATOR, IF_MISSING_RETURN_NONE) ?
                             //detected pure "rename"
-                            fmtPath(afterLast(relPathFrom, FILE_NAME_SEPARATOR, IF_MISSING_RETURN_ALL)) + L" " + arrowRight + L"\n" + //show short name only
+                            fmtPath(afterLast(relPathFrom, FILE_NAME_SEPARATOR, IF_MISSING_RETURN_ALL)) + L' ' + arrowRight + L'\n' + //show short name only
                             fmtPath(afterLast(relPathTo,   FILE_NAME_SEPARATOR, IF_MISSING_RETURN_ALL)) :
                             //"move" or "move + rename"
-                            fmtPath(relPathFrom) + L" " + arrowRight + L"\n" +
+                            fmtPath(relPathFrom) + L' ' + arrowRight + L'\n' +
                             fmtPath(relPathTo)) /*+ footer -> redundant */;
                 }
             break;
diff --git a/FreeFileSync/Source/base/file_hierarchy.h b/FreeFileSync/Source/base/file_hierarchy.h
index c717e41f..862f5169 100644
--- a/FreeFileSync/Source/base/file_hierarchy.h
+++ b/FreeFileSync/Source/base/file_hierarchy.h
@@ -425,12 +425,12 @@ public:
 
     //comparison result
     CompareFileResult getCategory() const { return cmpResult_; }
-    std::wstring getCatExtraDescription() const; //only filled if getCategory() == FILE_CONFLICT or FILE_DIFFERENT_METADATA
+    Zstringc getCatExtraDescription() const; //only filled if getCategory() == FILE_CONFLICT or FILE_DIFFERENT_METADATA
 
     //sync settings
     SyncDirection getSyncDir() const { return syncDir_; }
     void setSyncDir(SyncDirection newDir);
-    void setSyncDirConflict(const std::wstring& description); //set syncDir = SyncDirection::NONE + fill conflict description
+    void setSyncDirConflict(const Zstringc& description); //set syncDir = SyncDirection::NONE + fill conflict description
 
     bool isActive() const { return selectedForSync_; }
     void setActive(bool active);
@@ -449,8 +449,8 @@ public:
 
     //for use during init in "CompareProcess" only:
     template <CompareFileResult res> void setCategory();
-    void setCategoryConflict    (const Zstringw& description);
-    void setCategoryDiffMetadata(const Zstringw& description);
+    void setCategoryConflict    (const Zstringc& description);
+    void setCategoryDiffMetadata(const Zstringc& description);
 
 protected:
     FileSystemObject(const Zstring& itemNameL,
@@ -488,15 +488,16 @@ private:
     void propagateChangedItemName(const Zstring& itemNameOld); //required after any itemName changes
 
     //categorization
-    Zstringw cmpResultDescr_; //only filled if getCategory() == FILE_CONFLICT or FILE_DIFFERENT_METADATA
+    Zstringc cmpResultDescr_; //only filled if getCategory() == FILE_CONFLICT or FILE_DIFFERENT_METADATA
+    //conserve memory (avoid std::string SSO overhead + allow ref-counting!)
     CompareFileResult cmpResult_; //although this uses 4 bytes there is currently *no* space wasted in class layout!
 
     bool selectedForSync_ = true;
 
     //Note: we model *four* states with following two variables => "syncDirectionConflict is empty or syncDir == NONE" is a class invariant!!!
     SyncDirection syncDir_ = SyncDirection::NONE; //1 byte: optimize memory layout!
-    Zstringw syncDirectionConflict_; //non-empty if we have a conflict setting sync-direction
-    //get rid of std::wstring small string optimization (consumes 32/48 byte on VS2010 x86/x64!)
+    Zstringc syncDirectionConflict_; //non-empty if we have a conflict setting sync-direction
+    //conserve memory (avoid std::string SSO overhead + allow ref-counting!)
 
     Zstring itemNameL_; //slightly redundant under Linux, but on Windows the "same" file paths can differ in case
     Zstring itemNameR_; //use as indicator: an empty name means: not existing on this side!
@@ -723,10 +724,10 @@ CompareDirResult FolderPair::getDirCategory() const
 
 
 inline
-std::wstring FileSystemObject::getCatExtraDescription() const
+Zstringc FileSystemObject::getCatExtraDescription() const
 {
     assert(getCategory() == FILE_CONFLICT || getCategory() == FILE_DIFFERENT_METADATA);
-    return zen::copyStringTo<std::wstring>(cmpResultDescr_);
+    return cmpResultDescr_;
 }
 
 
@@ -741,11 +742,11 @@ void FileSystemObject::setSyncDir(SyncDirection newDir)
 
 
 inline
-void FileSystemObject::setSyncDirConflict(const std::wstring& description)
+void FileSystemObject::setSyncDirConflict(const Zstringc& description)
 {
     assert(!description.empty());
     syncDir_ = SyncDirection::NONE;
-    syncDirectionConflict_ = zen::copyStringTo<Zstringw>(description);
+    syncDirectionConflict_ = description;
 
     notifySyncCfgChanged();
 }
@@ -755,7 +756,7 @@ inline
 std::wstring FileSystemObject::getSyncOpConflict() const
 {
     assert(getSyncOperation() == SO_UNRESOLVED_CONFLICT);
-    return zen::copyStringTo<std::wstring>(syncDirectionConflict_);
+    return zen::utfTo<std::wstring>(syncDirectionConflict_);
 }
 
 
@@ -855,7 +856,7 @@ template <> void FileSystemObject::setCategory<FILE_LEFT_SIDE_ONLY>    () = dele
 template <> void FileSystemObject::setCategory<FILE_RIGHT_SIDE_ONLY>   () = delete; //
 
 inline
-void FileSystemObject::setCategoryConflict(const Zstringw& description)
+void FileSystemObject::setCategoryConflict(const Zstringc& description)
 {
     assert(!description.empty());
     cmpResult_ = FILE_CONFLICT;
@@ -863,7 +864,7 @@ void FileSystemObject::setCategoryConflict(const Zstringw& description)
 }
 
 inline
-void FileSystemObject::setCategoryDiffMetadata(const Zstringw& description)
+void FileSystemObject::setCategoryDiffMetadata(const Zstringc& description)
 {
     assert(!description.empty());
     cmpResult_ = FILE_DIFFERENT_METADATA;
diff --git a/FreeFileSync/Source/base/lock_holder.h b/FreeFileSync/Source/base/lock_holder.h
index ab24e9f4..87c075f9 100644
--- a/FreeFileSync/Source/base/lock_holder.h
+++ b/FreeFileSync/Source/base/lock_holder.h
@@ -5,7 +5,7 @@
 #include <zen/zstring.h>
 #include <zen/stl_tools.h>
 #include "dir_lock.h"
-#include "status_handler.h"
+#include "process_callback.h"
 
 
 namespace fff
@@ -43,8 +43,8 @@ public:
             for (const auto& [folderPath, error] : failedLocks)
             {
                 msg += L"\n\n";
-                //msg += fmtPath(folderPath) + L"\n" -> seems redundant
-                msg += replaceCpy(error.toString(), L"\n\n", L"\n");
+                //msg += fmtPath(folderPath) + L'\n' -> seems redundant
+                msg += replaceCpy(error.toString(), L"\n\n", L'\n');
             }
 
             pcb.reportWarning(msg, warnDirectoryLockFailed); //throw X
diff --git a/FreeFileSync/Source/base/parallel_scan.cpp b/FreeFileSync/Source/base/parallel_scan.cpp
index df2839fb..0bac2483 100644
--- a/FreeFileSync/Source/base/parallel_scan.cpp
+++ b/FreeFileSync/Source/base/parallel_scan.cpp
@@ -167,7 +167,7 @@ private:
             filePath = currentFile_;
         }
         if (parallelOpsTotal >= 2)
-            return L"[" + _P("1 thread", "%x threads", parallelOpsTotal) + L"] " + filePath;
+            return L'[' + _P("1 thread", "%x threads", parallelOpsTotal) + L"] " + filePath;
         else
             return filePath;
     }
@@ -202,8 +202,8 @@ struct TraverserConfig
     const FilterRef filter;
     const SymLinkHandling handleSymlinks;
 
-    std::map<Zstring, std::wstring>& failedDirReads;
-    std::map<Zstring, std::wstring>& failedItemReads;
+    std::map<Zstring, Zstringc>& failedDirReads;
+    std::map<Zstring, Zstringc>& failedItemReads;
 
     AsyncCallback& acb;
     const int threadIdx;
@@ -387,9 +387,9 @@ DirCallback::HandleError DirCallback::reportError(const std::wstring& msg, size_
     {
         case ON_ERROR_CONTINUE:
             if (itemName.empty())
-                cfg_.failedDirReads.emplace(beforeLast(parentRelPathPf_, FILE_NAME_SEPARATOR, IF_MISSING_RETURN_NONE), msg);
+                cfg_.failedDirReads.emplace(beforeLast(parentRelPathPf_, FILE_NAME_SEPARATOR, IF_MISSING_RETURN_NONE), utfTo<Zstringc>(msg));
             else
-                cfg_.failedItemReads.emplace(parentRelPathPf_ + itemName, msg);
+                cfg_.failedItemReads.emplace(parentRelPathPf_ + itemName, utfTo<Zstringc>(msg));
             return ON_ERROR_CONTINUE;
 
         case ON_ERROR_RETRY:
diff --git a/FreeFileSync/Source/base/parallel_scan.h b/FreeFileSync/Source/base/parallel_scan.h
index 9aa4bc82..1852d3fd 100644
--- a/FreeFileSync/Source/base/parallel_scan.h
+++ b/FreeFileSync/Source/base/parallel_scan.h
@@ -44,10 +44,10 @@ struct DirectoryValue
     FolderContainer folderCont;
 
     //relative paths (or empty string for root) for directories that could not be read (completely), e.g. access denied, or temporary network drop
-    std::map<Zstring, std::wstring> failedFolderReads; //with corresponding error message
+    std::map<Zstring, Zstringc> failedFolderReads; //with corresponding error message
 
     //relative paths (never empty) for failure to read single file/dir/symlink with corresponding error message
-    std::map<Zstring, std::wstring> failedItemReads;
+    std::map<Zstring, Zstringc> failedItemReads;
 };
 
 
diff --git a/FreeFileSync/Source/base/path_filter.h b/FreeFileSync/Source/base/path_filter.h
index f1087722..af7d6dc2 100644
--- a/FreeFileSync/Source/base/path_filter.h
+++ b/FreeFileSync/Source/base/path_filter.h
@@ -215,7 +215,7 @@ FilterRef constructFilter(const Zstring& includePhrase,
 {
     if (NameFilter::isNull(includePhrase, Zstring()))
     {
-        auto filterTmp = zen::makeSharedRef<NameFilter>(includePhrase2, excludePhrase + Zstr("\n") + excludePhrase2);
+        auto filterTmp = zen::makeSharedRef<NameFilter>(includePhrase2, excludePhrase + Zstr('\n') + excludePhrase2);
         if (filterTmp.ref().isNull())
             return zen::makeSharedRef<NullFilter>();
 
@@ -224,9 +224,9 @@ FilterRef constructFilter(const Zstring& includePhrase,
     else
     {
         if (NameFilter::isNull(includePhrase2, Zstring()))
-            return zen::makeSharedRef<NameFilter>(includePhrase, excludePhrase + Zstr("\n") + excludePhrase2);
+            return zen::makeSharedRef<NameFilter>(includePhrase, excludePhrase + Zstr('\n') + excludePhrase2);
         else
-            return zen::makeSharedRef<CombinedFilter>(NameFilter(includePhrase, excludePhrase + Zstr("\n") + excludePhrase2), NameFilter(includePhrase2, Zstring()));
+            return zen::makeSharedRef<CombinedFilter>(NameFilter(includePhrase, excludePhrase + Zstr('\n') + excludePhrase2), NameFilter(includePhrase2, Zstring()));
     }
 }
 
diff --git a/FreeFileSync/Source/base/resolve_path.cpp b/FreeFileSync/Source/base/resolve_path.cpp
index 83e6d226..f2737069 100644
--- a/FreeFileSync/Source/base/resolve_path.cpp
+++ b/FreeFileSync/Source/base/resolve_path.cpp
@@ -88,14 +88,14 @@ Zstring resolveRelativePath(const Zstring& relativePath)
 std::optional<Zstring> tryResolveMacro(const Zstring& macro) //macro without %-characters
 {
     //there exist environment variables named %TIME%, %DATE% so check for our internal macros first!
-    if (equalAsciiNoCase(macro, Zstr("time")))
-        return formatTime<Zstring>(Zstr("%H%M%S"));
+    if (equalAsciiNoCase(macro, "time"))
+        return formatTime(Zstr("%H%M%S"));
 
-    if (equalAsciiNoCase(macro, Zstr("date")))
-        return formatTime<Zstring>(FORMAT_ISO_DATE);
+    if (equalAsciiNoCase(macro, "date"))
+        return formatTime(formatIsoDateTag);
 
-    if (equalAsciiNoCase(macro, Zstr("timestamp")))
-        return formatTime<Zstring>(Zstr("%Y-%m-%d %H%M%S")); //e.g. "2012-05-15 131513"
+    if (equalAsciiNoCase(macro, "timestamp"))
+        return formatTime(Zstr("%Y-%m-%d %H%M%S")); //e.g. "2012-05-15 131513"
 
     Zstring timeStr;
     auto resolveTimePhrase = [&](const Zchar* phrase, const Zchar* format) -> bool
@@ -103,7 +103,7 @@ std::optional<Zstring> tryResolveMacro(const Zstring& macro) //macro without %-c
         if (!equalAsciiNoCase(macro, phrase))
             return false;
 
-        timeStr = formatTime<Zstring>(format);
+        timeStr = formatTime(format);
         return true;
     };
 
@@ -161,9 +161,9 @@ Zstring expandVolumeName(Zstring pathPhrase)  // [volname]:\folder       [volnam
 
     //we only expect the [.*] pattern at the beginning => do not touch dir names like "C:\somedir\[stuff]"
     trim(pathPhrase, true, false);
-    if (startsWith(pathPhrase, Zstr("[")))
+    if (startsWith(pathPhrase, Zstr('[')))
     {
-        const size_t posEnd = pathPhrase.find(Zstr("]"));
+        const size_t posEnd = pathPhrase.find(Zstr(']'));
         if (posEnd != Zstring::npos)
         {
             Zstring volName = Zstring(pathPhrase.c_str() + 1, posEnd - 1);
diff --git a/FreeFileSync/Source/base/status_handler_impl.h b/FreeFileSync/Source/base/status_handler_impl.h
index be6b6fa5..642b2cb0 100644
--- a/FreeFileSync/Source/base/status_handler_impl.h
+++ b/FreeFileSync/Source/base/status_handler_impl.h
@@ -207,7 +207,7 @@ private:
             const ThreadStatus* ts = getThreadStatus(); //call while holding "lockCurrentStatus_" lock!!
             return ts ? ts->taskIdx : static_cast<size_t>(-2);
         }();
-        return totalThreadCount_ > 1 ? L"[" + zen::numberTo<std::wstring>(taskIdx + 1) + L"] " : L"";
+        return totalThreadCount_ > 1 ? L'[' + zen::numberTo<std::wstring>(taskIdx + 1) + L"] " : L"";
     }
 #endif
 
@@ -252,7 +252,7 @@ private:
             }();
         }
         if (parallelOpsTotal >= 2)
-            return L"[" + _P("1 thread", "%x threads", parallelOpsTotal) + L"] " + statusMsg;
+            return L'[' + _P("1 thread", "%x threads", parallelOpsTotal) + L"] " + statusMsg;
         else
             return statusMsg;
     }
@@ -402,7 +402,7 @@ void massParallelExecute(const std::vector<std::pair<AbstractPath, ParallelWorkI
 
         auto& threadGroup = deviceThreadGroups.emplace(afsDevice, ThreadGroup<std::function<void()>>(
                                                            1,
-                                                           threadGroupName + " " + utfTo<std::string>(AFS::getDisplayPath(AbstractPath(afsDevice, AfsPath()))))).first->second;
+                                                           threadGroupName + ' ' + utfTo<std::string>(AFS::getDisplayPath(AbstractPath(afsDevice, AfsPath()))))).first->second;
 
         for (const std::pair<AbstractPath, ParallelWorkItem>* item : wl)
             threadGroup.run([&acb, statusPrio, &itemPath = item->first, &task = item->second]
diff --git a/FreeFileSync/Source/base/structures.cpp b/FreeFileSync/Source/base/structures.cpp
index cd275ac5..1e6758ac 100644
--- a/FreeFileSync/Source/base/structures.cpp
+++ b/FreeFileSync/Source/base/structures.cpp
@@ -10,69 +10,14 @@
 #include <ctime>
 #include <zen/i18n.h>
 #include <zen/time.h>
-#include "path_filter.h"
+//#include "path_filter.h"
 #include "../afs/concrete.h"
 
 using namespace zen;
 using namespace fff;
 
 
-std::vector<unsigned int> fff::fromTimeShiftPhrase(const std::wstring& timeShiftPhrase)
-{
-    std::wstring tmp = replaceCpy(timeShiftPhrase, L';', L','); //harmonize , ; and ' '
-    replace(tmp, L' ', L',');                                   //
-    replace(tmp, L'-', L""); //there is no negative shift => treat as positive!
-
-    std::set<unsigned int> minutes;
-    for (const std::wstring& part : split(tmp, L',', SplitType::SKIP_EMPTY))
-    {
-        if (contains(part, L':'))
-            minutes.insert(stringTo<unsigned int>(beforeFirst(part, L':', IF_MISSING_RETURN_NONE)) * 60 +
-                           stringTo<unsigned int>(afterFirst (part, L':', IF_MISSING_RETURN_NONE)));
-        else
-            minutes.insert(stringTo<unsigned int>(part) * 60);
-    }
-    minutes.erase(0);
-
-    return { minutes.begin(), minutes.end() };
-}
-
-
-std::wstring fff::toTimeShiftPhrase(const std::vector<unsigned int>& ignoreTimeShiftMinutes)
-{
-    std::wstring phrase;
-    for (auto it = ignoreTimeShiftMinutes.begin(); it != ignoreTimeShiftMinutes.end(); ++it)
-    {
-        if (it != ignoreTimeShiftMinutes.begin())
-            phrase += L", ";
-
-        phrase += numberTo<std::wstring>(*it / 60);
-        if (*it % 60 != 0)
-            phrase += L':' + printNumber<std::wstring>(L"%02d", static_cast<int>(*it % 60));
-    }
-    return phrase;
-}
-
-
-std::wstring fff::getVariantName(CompareVariant var)
-{
-    switch (var)
-    {
-        case CompareVariant::timeSize:
-            return _("File time and size");
-        case CompareVariant::content:
-            return _("File content");
-        case CompareVariant::size:
-            return _("File size");
-    }
-    assert(false);
-    return _("Error");
-}
-
-
-namespace
-{
-std::wstring getVariantNameImpl(DirectionConfig::Variant var, const wchar_t* arrowLeft, const wchar_t* arrowRight, const wchar_t* angleRight)
+std::wstring fff::getVariantNameImpl(DirectionConfig::Variant var, const wchar_t* arrowLeft, const wchar_t* arrowRight, const wchar_t* angleRight)
 {
     switch (var)
     {
@@ -88,28 +33,6 @@ std::wstring getVariantNameImpl(DirectionConfig::Variant var, const wchar_t* arr
     assert(false);
     return _("Error");
 }
-}
-
-
-std::wstring fff::getVariantName(DirectionConfig::Variant var)
-{
-#if 1
-    const wchar_t arrowLeft [] = L"<\u2013 ";
-    const wchar_t arrowRight[] = L" \u2013>";
-    const wchar_t angleRight[] = L" >";
-#else
-    //const wchar_t arrowLeft [] = L"\u2190 "; //unicode arrows -> too small
-    //const wchar_t arrowRight[] = L" \u2192"; //
-    //const wchar_t arrowLeft [] = L"\u25C4\u2013 "; //black triangle pointer
-    //const wchar_t arrowRight[] = L" \u2013\u25BA"; //
-    const wchar_t arrowLeft [] = L"\uFF1C\u2013 "; //fullwidth less-than + en dash
-    const wchar_t arrowRight[] =      L" \u2013\uFF1E"; //en dash + fullwidth greater-than
-    const wchar_t angleRight[] =            L" \uFF1E";
-    //=> drawback: - not drawn correctly before Vista
-    //             - RTL: the full width less-than is not mirrored automatically (=> Windows Unicode bug!)
-#endif
-    return getVariantNameImpl(var, arrowLeft, arrowRight, angleRight);
-}
 
 
 //use in sync log files where users expect ANSI: https://freefilesync.org/forum/viewtopic.php?t=4647
@@ -125,7 +48,7 @@ DirectionSet fff::extractDirections(const DirectionConfig& cfg)
     switch (cfg.var)
     {
         case DirectionConfig::TWO_WAY:
-            throw std::logic_error("there are no predefined directions for automatic mode! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+            throw std::logic_error("there are no predefined directions for automatic mode! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
 
         case DirectionConfig::MIRROR:
             output.exLeftSideOnly  = SyncDirection::RIGHT;
@@ -185,48 +108,6 @@ DirectionSet fff::getTwoWayUpdateSet()
 }
 
 
-std::wstring fff::getCompVariantName(const MainConfiguration& mainCfg)
-{
-    const CompareVariant firstVariant = mainCfg.firstPair.localCmpCfg ?
-                                        mainCfg.firstPair.localCmpCfg->compareVar :
-                                        mainCfg.cmpCfg.compareVar; //fallback to main sync cfg
-
-    //test if there's a deviating variant within the additional folder pairs
-    for (const LocalPairConfig& lpc : mainCfg.additionalPairs)
-    {
-        const CompareVariant thisVariant = lpc.localCmpCfg ?
-                                           lpc.localCmpCfg->compareVar :
-                                           mainCfg.cmpCfg.compareVar; //fallback to main sync cfg
-        if (thisVariant != firstVariant)
-            return _("Multiple...");
-    }
-
-    //seems to be all in sync...
-    return getVariantName(firstVariant);
-}
-
-
-std::wstring fff::getSyncVariantName(const MainConfiguration& mainCfg)
-{
-    const DirectionConfig::Variant firstVariant = mainCfg.firstPair.localSyncCfg ?
-                                                  mainCfg.firstPair.localSyncCfg->directionCfg.var :
-                                                  mainCfg.syncCfg.directionCfg.var; //fallback to main sync cfg
-
-    //test if there's a deviating variant within the additional folder pairs
-    for (const LocalPairConfig& lpc : mainCfg.additionalPairs)
-    {
-        const DirectionConfig::Variant thisVariant = lpc.localSyncCfg ?
-                                                     lpc.localSyncCfg->directionCfg.var :
-                                                     mainCfg.syncCfg.directionCfg.var;
-        if (thisVariant != firstVariant)
-            return _("Multiple...");
-    }
-
-    //seems to be all in sync...
-    return getVariantName(firstVariant);
-}
-
-
 size_t fff::getDeviceParallelOps(const std::map<AfsDevice, size_t>& deviceParallelOps, const AfsDevice& afsDevice)
 {
     auto it = deviceParallelOps.find(afsDevice);
@@ -398,205 +279,3 @@ void fff::resolveUnits(size_t timeSpan, UnitTime unitTimeSpan,
     sizeMinBy = resolve(sizeMin,  unitSizeMin, 0U);
     sizeMaxBy = resolve(sizeMax,  unitSizeMax, std::numeric_limits<uint64_t>::max());
 }
-
-
-namespace
-{
-FilterConfig mergeFilterConfig(const FilterConfig& global, const FilterConfig& local)
-{
-    FilterConfig out = local;
-
-    //hard filter
-    if (NameFilter::isNull(local.includeFilter, Zstring())) //fancy way of checking for "*" include
-        out.includeFilter = global.includeFilter;
-    //else : if both global and local include filters are set, only local filter is preserved
-
-    out.excludeFilter = trimCpy(trimCpy(global.excludeFilter) + Zstr("\n\n") + trimCpy(local.excludeFilter));
-
-    //soft filter
-    time_t   loctimeFrom  = 0;
-    uint64_t locSizeMinBy = 0;
-    uint64_t locSizeMaxBy = 0;
-    resolveUnits(out.timeSpan, out.unitTimeSpan,
-                 out.sizeMin,  out.unitSizeMin,
-                 out.sizeMax,  out.unitSizeMax,
-                 loctimeFrom,   //unit: UTC time, seconds
-                 locSizeMinBy,  //unit: bytes
-                 locSizeMaxBy); //unit: bytes
-
-    //soft filter
-    time_t   glotimeFrom  = 0;
-    uint64_t gloSizeMinBy = 0;
-    uint64_t gloSizeMaxBy = 0;
-    resolveUnits(global.timeSpan, global.unitTimeSpan,
-                 global.sizeMin,  global.unitSizeMin,
-                 global.sizeMax,  global.unitSizeMax,
-                 glotimeFrom,
-                 gloSizeMinBy,
-                 gloSizeMaxBy);
-
-    if (glotimeFrom > loctimeFrom)
-    {
-        out.timeSpan     = global.timeSpan;
-        out.unitTimeSpan = global.unitTimeSpan;
-    }
-    if (gloSizeMinBy > locSizeMinBy)
-    {
-        out.sizeMin     = global.sizeMin;
-        out.unitSizeMin = global.unitSizeMin;
-    }
-    if (gloSizeMaxBy < locSizeMaxBy)
-    {
-        out.sizeMax     = global.sizeMax;
-        out.unitSizeMax = global.unitSizeMax;
-    }
-    return out;
-}
-
-
-inline
-bool effectivelyEmpty(const LocalPairConfig& lpc)
-{
-    return trimCpy(lpc.folderPathPhraseLeft ).empty() &&
-           trimCpy(lpc.folderPathPhraseRight).empty();
-}
-}
-
-
-MainConfiguration fff::merge(const std::vector<MainConfiguration>& mainCfgs)
-{
-    assert(!mainCfgs.empty());
-    if (mainCfgs.empty())
-        return MainConfiguration();
-
-    if (mainCfgs.size() == 1) //mergeConfigFilesImpl relies on this!
-        return mainCfgs[0];   //
-
-    //merge folder pair config
-    std::vector<LocalPairConfig> mergedCfgs;
-    for (const MainConfiguration& mainCfg : mainCfgs)
-    {
-        std::vector<LocalPairConfig> tmpCfgs;
-
-        //skip empty folder pairs
-        if (!effectivelyEmpty(mainCfg.firstPair))
-            tmpCfgs.push_back(mainCfg.firstPair);
-
-        for (const LocalPairConfig& lpc : mainCfg.additionalPairs)
-            if (!effectivelyEmpty(lpc))
-                tmpCfgs.push_back(lpc);
-
-        //move all configuration down to item level
-        for (LocalPairConfig& lpc : tmpCfgs)
-        {
-            if (!lpc.localCmpCfg)
-                lpc.localCmpCfg = mainCfg.cmpCfg;
-
-            if (!lpc.localSyncCfg)
-                lpc.localSyncCfg = mainCfg.syncCfg;
-
-            lpc.localFilter = mergeFilterConfig(mainCfg.globalFilter, lpc.localFilter);
-        }
-        append(mergedCfgs, tmpCfgs);
-    }
-
-    if (mergedCfgs.empty())
-        return MainConfiguration();
-
-    //optimization: remove redundant configuration
-
-    //########################################################################################################################
-    //find out which comparison and synchronization setting are used most often and use them as new "header"
-    std::vector<std::pair<CompConfig, int>> cmpCfgStat;
-    std::vector<std::pair<SyncConfig, int>> syncCfgStat;
-    for (const LocalPairConfig& lpc : mergedCfgs)
-    {
-        //a rather inefficient algorithm, but it does not require a less-than operator:
-        {
-            const CompConfig& cmpCfg = *lpc.localCmpCfg;
-
-            auto it = std::find_if(cmpCfgStat.begin(), cmpCfgStat.end(),
-            [&](const std::pair<CompConfig, int>& entry) { return effectivelyEqual(entry.first, cmpCfg); });
-            if (it == cmpCfgStat.end())
-                cmpCfgStat.emplace_back(cmpCfg, 1);
-            else
-                ++(it->second);
-        }
-        {
-            const SyncConfig& syncCfg = *lpc.localSyncCfg;
-
-            auto it = std::find_if(syncCfgStat.begin(), syncCfgStat.end(),
-            [&](const std::pair<SyncConfig, int>& entry) { return effectivelyEqual(entry.first, syncCfg); });
-            if (it == syncCfgStat.end())
-                syncCfgStat.emplace_back(syncCfg, 1);
-            else
-                ++(it->second);
-        }
-    }
-
-    //set most-used comparison and synchronization settings as new header options
-    const CompConfig cmpCfgHead = cmpCfgStat.empty() ? CompConfig() :
-                                  std::max_element(cmpCfgStat.begin(), cmpCfgStat.end(),
-    [](const std::pair<CompConfig, int>& lhs, const std::pair<CompConfig, int>& rhs) { return lhs.second < rhs.second; })->first;
-
-    const SyncConfig syncCfgHead = syncCfgStat.empty() ? SyncConfig() :
-                                   std::max_element(syncCfgStat.begin(), syncCfgStat.end(),
-    [](const std::pair<SyncConfig, int>& lhs, const std::pair<SyncConfig, int>& rhs) { return lhs.second < rhs.second; })->first;
-    //########################################################################################################################
-
-    FilterConfig globalFilter;
-    const bool allFiltersEqual = std::all_of(mergedCfgs.begin(), mergedCfgs.end(), [&](const LocalPairConfig& lpc) { return lpc.localFilter == mergedCfgs[0].localFilter; });
-    if (allFiltersEqual)
-        globalFilter = mergedCfgs[0].localFilter;
-
-    //strip redundancy...
-    for (LocalPairConfig& lpc : mergedCfgs)
-    {
-        //if local config matches output global config we don't need local one
-        if (lpc.localCmpCfg &&
-            effectivelyEqual(*lpc.localCmpCfg, cmpCfgHead))
-            lpc.localCmpCfg = {};
-
-        if (lpc.localSyncCfg &&
-            effectivelyEqual(*lpc.localSyncCfg, syncCfgHead))
-            lpc.localSyncCfg = {};
-
-        if (allFiltersEqual) //use global filter in this case
-            lpc.localFilter = FilterConfig();
-    }
-
-    std::map<AfsDevice, size_t> mergedParallelOps;
-    for (const MainConfiguration& mainCfg : mainCfgs)
-        for (const auto& [rootPath, parallelOps] : mainCfg.deviceParallelOps)
-            mergedParallelOps[rootPath] = std::max(mergedParallelOps[rootPath], parallelOps);
-
-    //final assembly
-    MainConfiguration cfgOut;
-    cfgOut.cmpCfg       = cmpCfgHead;
-    cfgOut.syncCfg      = syncCfgHead;
-    cfgOut.globalFilter = globalFilter;
-    cfgOut.firstPair    = mergedCfgs[0];
-    cfgOut.additionalPairs.assign(mergedCfgs.begin() + 1, mergedCfgs.end());
-    cfgOut.deviceParallelOps = mergedParallelOps;
-
-    cfgOut.ignoreErrors = std::all_of(mainCfgs.begin(), mainCfgs.end(), [](const MainConfiguration& mainCfg) { return mainCfg.ignoreErrors; });
-
-    cfgOut.automaticRetryCount = std::max_element(mainCfgs.begin(), mainCfgs.end(),
-    [](const MainConfiguration& lhs, const MainConfiguration& rhs) { return lhs.automaticRetryCount < rhs.automaticRetryCount; })->automaticRetryCount;
-
-    cfgOut.automaticRetryDelay = std::max_element(mainCfgs.begin(), mainCfgs.end(),
-    [](const MainConfiguration& lhs, const MainConfiguration& rhs) { return lhs.automaticRetryDelay < rhs.automaticRetryDelay; })->automaticRetryDelay;
-
-    for (const MainConfiguration& mainCfg : mainCfgs)
-        if (!mainCfg.altLogFolderPathPhrase.empty())
-        {
-            cfgOut.altLogFolderPathPhrase = mainCfg.altLogFolderPathPhrase;
-            break;
-        }
-
-    //cfgOut.postSyncCommand   = -> better leave at default ... !?
-    //cfgOut.postSyncCondition = ->
-    //cfgOut.emailNotifyAddress   = -> better leave at default ... !?
-    //cfgOut.emailNotifyCondition = ->
-    return cfgOut;
-}
diff --git a/FreeFileSync/Source/base/structures.h b/FreeFileSync/Source/base/structures.h
index 5ee9708a..11e98948 100644
--- a/FreeFileSync/Source/base/structures.h
+++ b/FreeFileSync/Source/base/structures.h
@@ -25,8 +25,6 @@ enum class CompareVariant
     size
 };
 
-std::wstring getVariantName(CompareVariant var);
-
 
 enum class SymLinkHandling
 {
@@ -150,7 +148,7 @@ bool detectMovedFilesEnabled   (const DirectionConfig& cfg);
 
 DirectionSet extractDirections(const DirectionConfig& cfg); //get sync directions: DON'T call for DirectionConfig::TWO_WAY!
 
-std::wstring getVariantName      (DirectionConfig::Variant var);
+std::wstring getVariantNameImpl(DirectionConfig::Variant var, const wchar_t* arrowLeft, const wchar_t* arrowRight, const wchar_t* angleRight);
 std::wstring getVariantNameForLog(DirectionConfig::Variant var);
 
 inline
@@ -191,10 +189,6 @@ inline bool operator!=(const CompConfig& lhs, const CompConfig& rhs) { return !(
 inline
 bool effectivelyEqual(const CompConfig& lhs, const CompConfig& rhs) { return lhs == rhs; } //no change in behavior
 
-//convert "ignoreTimeShiftMinutes" into compact format:
-std::vector<unsigned int> fromTimeShiftPhrase(const std::wstring& timeShiftPhrase);
-std::wstring              toTimeShiftPhrase  (const std::vector<unsigned int>& ignoreTimeShiftMinutes);
-
 
 enum class DeletionPolicy
 {
@@ -423,12 +417,10 @@ struct MainConfiguration
 
     Zstring altLogFolderPathPhrase; //fill to use different log file folder (other than the default %appdata%\FreeFileSync\Logs)
 
-    Zstring emailNotifyAddress; //optional
+    std::string emailNotifyAddress; //optional
     ResultsNotification emailNotifyCondition = ResultsNotification::always;
 };
 
-std::wstring getCompVariantName(const MainConfiguration& mainCfg);
-std::wstring getSyncVariantName(const MainConfiguration& mainCfg);
 
 size_t getDeviceParallelOps(const std::map<AfsDevice, size_t>& deviceParallelOps, const AfsDevice& afsDevice);
 void   setDeviceParallelOps(      std::map<AfsDevice, size_t>& deviceParallelOps, const AfsDevice& afsDevice, size_t parallelOps);
@@ -455,8 +447,37 @@ bool operator==(const MainConfiguration& lhs, const MainConfiguration& rhs)
 }
 
 
-//facilitate drag & drop config merge:
-MainConfiguration merge(const std::vector<MainConfiguration>& mainCfgs);
+struct WarningDialogs
+{
+    bool warnFolderNotExisting          = true;
+    bool warnFoldersDifferInCase        = true;
+    bool warnDependentFolderPair        = true;
+    bool warnDependentBaseFolders       = true;
+    bool warnSignificantDifference      = true;
+    bool warnNotEnoughDiskSpace         = true;
+    bool warnUnresolvedConflicts        = true;
+    bool warnModificationTimeError      = true;
+    bool warnRecyclerMissing            = true;
+    bool warnInputFieldEmpty            = true;
+    bool warnDirectoryLockFailed        = true;
+    bool warnVersioningFolderPartOfSync = true;
+};
+inline bool operator==(const WarningDialogs& lhs, const WarningDialogs& rhs)
+{
+    return lhs.warnFolderNotExisting          == rhs.warnFolderNotExisting     &&
+           lhs.warnFoldersDifferInCase        == rhs.warnFoldersDifferInCase   &&
+           lhs.warnDependentFolderPair        == rhs.warnDependentFolderPair   &&
+           lhs.warnDependentBaseFolders       == rhs.warnDependentBaseFolders  &&
+           lhs.warnSignificantDifference      == rhs.warnSignificantDifference &&
+           lhs.warnNotEnoughDiskSpace         == rhs.warnNotEnoughDiskSpace    &&
+           lhs.warnUnresolvedConflicts        == rhs.warnUnresolvedConflicts   &&
+           lhs.warnModificationTimeError      == rhs.warnModificationTimeError &&
+           lhs.warnRecyclerMissing            == rhs.warnRecyclerMissing       &&
+           lhs.warnInputFieldEmpty            == rhs.warnInputFieldEmpty       &&
+           lhs.warnDirectoryLockFailed        == rhs.warnDirectoryLockFailed   &&
+           lhs.warnVersioningFolderPartOfSync == rhs.warnVersioningFolderPartOfSync;
+}
+inline bool operator!=(const WarningDialogs& lhs, const WarningDialogs& rhs) { return !(lhs == rhs); }
 }
 
 #endif //STRUCTURES_H_8210478915019450901745
diff --git a/FreeFileSync/Source/base/synchronization.cpp b/FreeFileSync/Source/base/synchronization.cpp
index 097e3cf0..38ad1771 100644
--- a/FreeFileSync/Source/base/synchronization.cpp
+++ b/FreeFileSync/Source/base/synchronization.cpp
@@ -124,7 +124,9 @@ void SyncStatistics::processFile(const FilePair& file)
             break;
 
         case SO_UNRESOLVED_CONFLICT:
-            conflictMsgs_.push_back({ file.getRelativePathAny(), file.getSyncOpConflict() });
+            ++conflictCount_;
+            if (conflictsPreview_.size() < SYNC_STATS_CONFLICTS_MAX)
+                conflictsPreview_.push_back({ file.getRelativePathAny(), file.getSyncOpConflict() });
             break;
 
         case SO_COPY_METADATA_TO_LEFT:
@@ -178,7 +180,9 @@ void SyncStatistics::processLink(const SymlinkPair& link)
             break;
 
         case SO_UNRESOLVED_CONFLICT:
-            conflictMsgs_.push_back({ link.getRelativePathAny(), link.getSyncOpConflict() });
+            ++conflictCount_;
+            if (conflictsPreview_.size() < SYNC_STATS_CONFLICTS_MAX)
+                conflictsPreview_.push_back({ link.getRelativePathAny(), link.getSyncOpConflict() });
             break;
 
         case SO_MOVE_LEFT_FROM:
@@ -218,7 +222,9 @@ void SyncStatistics::processFolder(const FolderPair& folder)
             break;
 
         case SO_UNRESOLVED_CONFLICT:
-            conflictMsgs_.push_back({ folder.getRelativePathAny(), folder.getSyncOpConflict() });
+            ++conflictCount_;
+            if (conflictsPreview_.size() < SYNC_STATS_CONFLICTS_MAX)
+                conflictsPreview_.push_back({ folder.getRelativePathAny(), folder.getSyncOpConflict() });
             break;
 
         case SO_OVERWRITE_LEFT:
@@ -464,8 +470,8 @@ void verifyFiles(const AbstractPath& sourcePath, const AbstractPath& targetPath,
 
         if (!filesHaveSameContent(sourcePath, targetPath, notifyUnbufferedIO)) //throw FileError, X
             throw FileError(replaceCpy(replaceCpy(_("%x and %y have different content."),
-                                                  L"%x", L"\n" + fmtPath(AFS::getDisplayPath(sourcePath))),
-                                       L"%y", L"\n" + fmtPath(AFS::getDisplayPath(targetPath))));
+                                                  L"%x", L'\n' + fmtPath(AFS::getDisplayPath(sourcePath))),
+                                       L"%y", L'\n' + fmtPath(AFS::getDisplayPath(targetPath))));
     }
     catch (const FileError& e) //add some context to error message
     {
@@ -747,7 +753,7 @@ void DeletionHandler::removeDirWithCallback(const AbstractPath& folderPath,//thr
             //callbacks run *outside* singleThread_ lock! => fine
             auto notifyMove = [&statReporter](const std::wstring& statusText, const std::wstring& displayPathFrom, const std::wstring& displayPathTo)
             {
-                statReporter.updateStatus(replaceCpy(replaceCpy(statusText, L"%x", L"\n" + fmtPath(displayPathFrom)), L"%y", L"\n" + fmtPath(displayPathTo))); //throw ThreadInterruption
+                statReporter.updateStatus(replaceCpy(replaceCpy(statusText, L"%x", L'\n' + fmtPath(displayPathFrom)), L"%y", L'\n' + fmtPath(displayPathTo))); //throw ThreadInterruption
                 statReporter.reportDelta(1, 0); //it would be more correct to report *after* work was done!
                 warn_static("=> indeed; fix!?")
             };
@@ -984,7 +990,7 @@ private:
     void reportInfo(const std::wstring& rawText, const std::wstring& displayPath) { acb_.reportInfo(replaceCpy(rawText, L"%x", fmtPath(displayPath))); }
     void reportInfo(const std::wstring& rawText, const std::wstring& displayPath1, const std::wstring& displayPath2) //throw ThreadInterruption
     {
-        acb_.reportInfo(replaceCpy(replaceCpy(rawText, L"%x", L"\n" + fmtPath(displayPath1)), L"%y", L"\n" + fmtPath(displayPath2))); //throw ThreadInterruption
+        acb_.reportInfo(replaceCpy(replaceCpy(rawText, L"%x", L'\n' + fmtPath(displayPath1)), L"%y", L'\n' + fmtPath(displayPath2))); //throw ThreadInterruption
     }
 
     //target existing after onDeleteTargetFile(): undefined behavior! (fail/overwrite/auto-rename)
@@ -1523,8 +1529,8 @@ void FolderPairSyncer::synchronizeFileInt(FilePair& file, SyncOperation syncOp)
                 catch (const FileError& e2) //more relevant than previous exception (which could be "item not found")
                 {
                     throw FileError(replaceCpy(replaceCpy(_("Cannot copy file %x to %y."),
-                                                          L"%x", L"\n" + fmtPath(AFS::getDisplayPath(file.getAbstractPath<sideSrc>()))),
-                                               L"%y", L"\n" + fmtPath(AFS::getDisplayPath(targetPath))), replaceCpy(e2.toString(), L"\n\n", L"\n"));
+                                                          L"%x", L'\n' + fmtPath(AFS::getDisplayPath(file.getAbstractPath<sideSrc>()))),
+                                               L"%y", L'\n' + fmtPath(AFS::getDisplayPath(targetPath))), replaceCpy(e2.toString(), L"\n\n", L'\n'));
                 }
                 //do not check on type (symlink, file, folder) -> if there is a type change, FFS should not be quiet about it!
                 if (!sourceExists)
@@ -1745,8 +1751,8 @@ void FolderPairSyncer::synchronizeLinkInt(SymlinkPair& symlink, SyncOperation sy
                 catch (const FileError& e2) //more relevant than previous exception (which could be "item not found")
                 {
                     throw FileError(replaceCpy(replaceCpy(_("Cannot copy symbolic link %x to %y."),
-                                                          L"%x", L"\n" + fmtPath(AFS::getDisplayPath(symlink.getAbstractPath<sideSrc>()))),
-                                               L"%y", L"\n" + fmtPath(AFS::getDisplayPath(targetPath))), replaceCpy(e2.toString(), L"\n\n", L"\n"));
+                                                          L"%x", L'\n' + fmtPath(AFS::getDisplayPath(symlink.getAbstractPath<sideSrc>()))),
+                                               L"%y", L'\n' + fmtPath(AFS::getDisplayPath(targetPath))), replaceCpy(e2.toString(), L"\n\n", L'\n'));
                 }
                 //do not check on type (symlink, file, folder) -> if there is a type change, FFS should not be quiet about it!
                 if (!sourceExists)
@@ -2137,7 +2143,7 @@ void fff::synchronize(const std::chrono::system_clock::time_point& syncStartTime
     //PERF_START;
 
     if (syncConfig.size() != folderCmp.size())
-        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
 
     //aggregate basic information
     std::vector<SyncStatistics> folderPairStats;
@@ -2189,7 +2195,7 @@ void fff::synchronize(const std::chrono::system_clock::time_point& syncStartTime
 
     std::vector<FolderPairJobType> jobType(folderCmp.size(), FolderPairJobType::PROCESS); //folder pairs may be skipped after fatal errors were found
 
-    std::map<const BaseFolderPair*, std::vector<SyncStatistics::ConflictInfo>> checkUnresolvedConflicts;
+    std::map<const BaseFolderPair*, std::pair<int, std::vector<SyncStatistics::ConflictInfo>>> checkUnresolvedConflicts;
 
     std::vector<std::tuple<AbstractPath, const PathFilter*, bool /*write access*/>> checkReadWriteBaseFolders;
 
@@ -2216,7 +2222,7 @@ void fff::synchronize(const std::chrono::system_clock::time_point& syncStartTime
         const AbstractPath versioningFolderPath = createAbstractPath(folderPairCfg.versioningFolderPhrase);
 
         //aggregate *all* conflicts:
-        checkUnresolvedConflicts[&baseFolder] = folderPairStat.getConflicts();
+        checkUnresolvedConflicts[&baseFolder] = std::pair(folderPairStat.conflictCount(), folderPairStat.getConflictsPreview());
 
         //consider *all* paths that might be used during versioning limit at some time
         if (folderPairCfg.handleDeletion == DeletionPolicy::versioning &&
@@ -2375,20 +2381,27 @@ void fff::synchronize(const std::chrono::system_clock::time_point& syncStartTime
     //-----------------------------------------------------------------
 
     //check if unresolved conflicts exist
-    if (std::any_of(checkUnresolvedConflicts.begin(), checkUnresolvedConflicts.end(), [](const auto& item) { return !item.second.empty(); }))
+    if (std::any_of(checkUnresolvedConflicts.begin(), checkUnresolvedConflicts.end(), [](const auto& item) { return item.second.first > 0; }))
     {
         std::wstring msg = _("The following items have unresolved conflicts and will not be synchronized:");
 
         for (const auto& [baseFolder, conflicts] : checkUnresolvedConflicts)
-            if (!conflicts.empty())
+        {
+            const auto& [conflictCount, conflictPreview] = conflicts;
+            if (conflictCount > 0)
             {
-                msg += L"\n\n" + _("Folder pair:") + L" " +
+                msg += L"\n\n" + _("Folder pair:") + L' ' +
                        AFS::getDisplayPath(baseFolder->getAbstractPath< LEFT_SIDE>()) + L" <-> " +
                        AFS::getDisplayPath(baseFolder->getAbstractPath<RIGHT_SIDE>());
 
-                for (const SyncStatistics::ConflictInfo& item : conflicts) //show *all* conflicts in warning message
-                    msg += L"\n" + utfTo<std::wstring>(item.relPath) + L": " + item.msg;
+                for (const SyncStatistics::ConflictInfo& item : conflictPreview)
+                    msg += L'\n' + utfTo<std::wstring>(item.relPath) + L": " + item.msg;
+
+                if (makeUnsigned(conflictCount) > conflictPreview.size())
+                    msg += L"\n  [...]  " + replaceCpy(_P("Showing %y of 1 row", "Showing %y of %x rows", conflictCount), //%x used as plural form placeholder!
+                                                       L"%y", formatNumber(conflictPreview.size()));
             }
+        }
 
         callback.reportWarning(msg, warnings.warnUnresolvedConflicts);
     }
@@ -2400,7 +2413,7 @@ void fff::synchronize(const std::chrono::system_clock::time_point& syncStartTime
 
         for (const auto& [folderPathL, folderPathR] : checkSignificantDiffPairs)
             msg += L"\n\n" +
-                   AFS::getDisplayPath(folderPathL) + L" <-> " + L"\n" +
+                   AFS::getDisplayPath(folderPathL) + L" <-> " + L'\n' +
                    AFS::getDisplayPath(folderPathR);
 
         callback.reportWarning(msg, warnings.warnSignificantDifference);
@@ -2412,9 +2425,9 @@ void fff::synchronize(const std::chrono::system_clock::time_point& syncStartTime
         std::wstring msg = _("Not enough free disk space available in:");
 
         for (const auto& [folderPath, space] : checkDiskSpaceMissing)
-            msg += L"\n\n" + AFS::getDisplayPath(folderPath) + L"\n" +
-                   _("Required:")  + L" " + formatFilesizeShort(space.first)  + L"\n" +
-                   _("Available:") + L" " + formatFilesizeShort(space.second);
+            msg += L"\n\n" + AFS::getDisplayPath(folderPath) + L'\n' +
+                   _("Required:")  + L' ' + formatFilesizeShort(space.first)  + L'\n' +
+                   _("Available:") + L' ' + formatFilesizeShort(space.second);
 
         callback.reportWarning(msg, warnings.warnNotEnoughDiskSpace);
     }
@@ -2424,10 +2437,10 @@ void fff::synchronize(const std::chrono::system_clock::time_point& syncStartTime
         std::wstring msg;
         for (const auto& [folderPath, supported] : recyclerSupported)
             if (!supported)
-                msg += L"\n" + AFS::getDisplayPath(folderPath);
+                msg += L'\n' + AFS::getDisplayPath(folderPath);
 
         if (!msg.empty())
-            callback.reportWarning(_("The recycle bin is not supported by the following folders. Deleted or overwritten files will not be able to be restored:") + L"\n" + msg,
+            callback.reportWarning(_("The recycle bin is not supported by the following folders. Deleted or overwritten files will not be able to be restored:") + L'\n' + msg,
                                    warnings.warnRecyclerMissing);
     }
 
@@ -2449,11 +2462,11 @@ void fff::synchronize(const std::chrono::system_clock::time_point& syncStartTime
 
         if (!dependentFolders.empty())
         {
-            std::wstring msg = _("Some files will be synchronized as part of multiple base folders.") + L"\n" +
-                               _("To avoid conflicts, set up exclude filters so that each updated file is included by only one base folder.") + L"\n";
+            std::wstring msg = _("Some files will be synchronized as part of multiple base folders.") + L'\n' +
+                               _("To avoid conflicts, set up exclude filters so that each updated file is included by only one base folder.") + L'\n';
 
             for (const AbstractPath& baseFolderPath : dependentFolders)
-                msg += L"\n" + AFS::getDisplayPath(baseFolderPath);
+                msg += L'\n' + AFS::getDisplayPath(baseFolderPath);
 
             callback.reportWarning(msg, warnings.warnDependentBaseFolders);
         }
@@ -2470,9 +2483,9 @@ void fff::synchronize(const std::chrono::system_clock::time_point& syncStartTime
                 if (std::optional<PathDependency> pd = getPathDependency(versioningFolderPath, NullFilter(), folderPath, *filter))
                 {
                     std::wstring line = L"\n\n" + _("Versioning folder:") + L" \t" + AFS::getDisplayPath(versioningFolderPath) +
-                                        L"\n"   + _("Base folder:")       + L" \t" + AFS::getDisplayPath(folderPath);
+                                        L'\n'   + _("Base folder:")       + L" \t" + AFS::getDisplayPath(folderPath);
                     if (pd->basePathParent == folderPath && !pd->relPath.empty())
-                        line += L"\n" + _("Exclude:") + L" \t" + utfTo<std::wstring>(FILE_NAME_SEPARATOR + pd->relPath + FILE_NAME_SEPARATOR);
+                        line += L'\n' + _("Exclude:") + L" \t" + utfTo<std::wstring>(FILE_NAME_SEPARATOR + pd->relPath + FILE_NAME_SEPARATOR);
 
                     uniqueMsgs[folderPath] = line;
                 }
@@ -2480,7 +2493,7 @@ void fff::synchronize(const std::chrono::system_clock::time_point& syncStartTime
                 msg += perFolderMsg;
         }
         if (!msg.empty())
-            callback.reportWarning(_("The versioning folder is contained in a base folder.") + L"\n" +
+            callback.reportWarning(_("The versioning folder is contained in a base folder.") + L'\n' +
                                    _("The folder should be excluded from synchronization via filter.") + msg, warnings.warnVersioningFolderPartOfSync);
     }
 
@@ -2497,9 +2510,9 @@ void fff::synchronize(const std::chrono::system_clock::time_point& syncStartTime
             for (const auto& [key, aliases] : ciPathAliases)
                 if (aliases.size() > 1)
                 {
-                    msg += L"\n";
+                    msg += L'\n';
                     for (const AbstractPath& aliasPath : aliases)
-                        msg += L"\n" + AFS::getDisplayPath(aliasPath);
+                        msg += L'\n' + AFS::getDisplayPath(aliasPath);
                 }
             callback.reportWarning(msg, warnings.warnFoldersDifferInCase); //throw X
         }
@@ -2521,7 +2534,7 @@ void fff::synchronize(const std::chrono::system_clock::time_point& syncStartTime
 			std::wstring msg;
 			for (const FileError& e : errorsModTime)
 			{
-				std::wstring singleMsg = replaceCpy(e.toString(), L"\n\n", L"\n");
+				std::wstring singleMsg = replaceCpy(e.toString(), L"\n\n", L'\n');
 				msg += singleMsg + L"\n\n";
 			}
 			msg.resize(msg.size() - 2);
@@ -2571,8 +2584,8 @@ void fff::synchronize(const std::chrono::system_clock::time_point& syncStartTime
 
             //------------------------------------------------------------------------------------------
             if (folderCmp.size() > 1)
-                callback.reportInfo(_("Synchronizing folder pair:") + L" " + getVariantNameForLog(folderPairCfg.syncVariant) + L"\n" + //throw X
-                                    L"    " + AFS::getDisplayPath(baseFolder.getAbstractPath< LEFT_SIDE>()) + L"\n" +
+                callback.reportInfo(_("Synchronizing folder pair:") + L' ' + getVariantNameForLog(folderPairCfg.syncVariant) + L'\n' + //throw X
+                                    L"    " + AFS::getDisplayPath(baseFolder.getAbstractPath< LEFT_SIDE>()) + L'\n' +
                                     L"    " + AFS::getDisplayPath(baseFolder.getAbstractPath<RIGHT_SIDE>()));
             //------------------------------------------------------------------------------------------
 
diff --git a/FreeFileSync/Source/base/synchronization.h b/FreeFileSync/Source/base/synchronization.h
index c0c5df35..275918b4 100644
--- a/FreeFileSync/Source/base/synchronization.h
+++ b/FreeFileSync/Source/base/synchronization.h
@@ -8,7 +8,8 @@
 #define SYNCHRONIZATION_H_8913470815943295
 
 #include <chrono>
-#include "config.h"
+//#include "config.h"
+#include "structures.h"
 #include "file_hierarchy.h"
 #include "process_callback.h"
 
@@ -38,8 +39,6 @@ public:
     template <SelectedSide side>
     bool expectPhysicalDeletion() const { return SelectParam<side>::ref(physicalDeleteLeft_, physicalDeleteRight_); }
 
-    int conflictCount() const { return static_cast<int>(conflictMsgs_.size()); }
-
     int64_t getBytesToProcess() const { return bytesToProcess_; }
     size_t  rowCount         () const { return rowsTotal_; }
 
@@ -48,7 +47,8 @@ public:
         Zstring relPath;
         std::wstring msg;
     };
-    const std::vector<ConflictInfo>& getConflicts() const { return conflictMsgs_; }
+    const std::vector<ConflictInfo>& getConflictsPreview() const { return conflictsPreview_; }
+    int conflictCount() const { return conflictCount_; }
 
 private:
     void recurse(const ContainerObject& hierObj);
@@ -65,9 +65,14 @@ private:
     int deleteRight_ = 0;
     bool physicalDeleteLeft_  = false; //at least 1 item will be deleted; considers most "update" cases which also delete items
     bool physicalDeleteRight_ = false; //
-    std::vector<ConflictInfo> conflictMsgs_; //conflict texts to display as a warning message
+
     int64_t bytesToProcess_ = 0;
     size_t rowsTotal_ = 0;
+
+    int conflictCount_ = 0;
+    std::vector<ConflictInfo> conflictsPreview_; //conflict texts to display as a warning message
+    static const size_t SYNC_STATS_CONFLICTS_MAX = 25; //=> consider memory consumption, log file size, email size!
+    //limit conflict count! e.g. there may be hundred thousands of "same date but a different size"
 };
 
 
diff --git a/FreeFileSync/Source/base/versioning.cpp b/FreeFileSync/Source/base/versioning.cpp
index c2b95f8d..bf596d11 100644
--- a/FreeFileSync/Source/base/versioning.cpp
+++ b/FreeFileSync/Source/base/versioning.cpp
@@ -422,14 +422,14 @@ void fff::applyVersioningLimit(const std::set<VersioningLimitFolder>& folderLimi
 
             if (!status.failedChecks.empty())
             {
-                std::wstring msg = _("Cannot find the following folders:") + L"\n";
+                std::wstring msg = _("Cannot find the following folders:") + L'\n';
 
                 for (const auto& [folderPath, error] : status.failedChecks)
-                    msg += L"\n" + AFS::getDisplayPath(folderPath);
+                    msg += L'\n' + AFS::getDisplayPath(folderPath);
 
                 msg += L"\n___________________________________________";
                 for (const auto& [folderPath, error] : status.failedChecks)
-                    msg += L"\n\n" + replaceCpy(error.toString(), L"\n\n", L"\n");
+                    msg += L"\n\n" + replaceCpy(error.toString(), L"\n\n", L'\n');
 
                 throw FileError(msg);
             }
@@ -453,7 +453,7 @@ void fff::applyVersioningLimit(const std::set<VersioningLimitFolder>& folderLimi
         return AFS::TraverserCallback::ON_ERROR_CONTINUE;
     };
 
-    const std::wstring textScanning = _("Searching for old file versions:") + L" ";
+    const std::wstring textScanning = _("Searching for old file versions:") + L' ';
 
     auto onStatusUpdate = [&](const std::wstring& statusLine, int itemsTotal)
     {
@@ -538,7 +538,7 @@ void fff::applyVersioningLimit(const std::set<VersioningLimitFolder>& folderLimi
 
     //--------- remove excess file versions ---------
     Protected<std::map<AbstractPath, size_t>&> folderItemCountShared(folderItemCount);
-    const std::wstring txtRemoving = _("Removing old file versions:") + L" ";
+    const std::wstring txtRemoving = _("Removing old file versions:") + L' ';
     const std::wstring txtDeletingFolder = _("Deleting folder %x");
 
     std::function<void(const AbstractPath& folderPath, AsyncCallback& acb)> deleteEmptyFolderTask;
diff --git a/FreeFileSync/Source/base/versioning.h b/FreeFileSync/Source/base/versioning.h
index 9c0a9b43..d5edb345 100644
--- a/FreeFileSync/Source/base/versioning.h
+++ b/FreeFileSync/Source/base/versioning.h
@@ -39,12 +39,12 @@ public:
         versioningFolderPath_(versioningFolderPath),
         versioningStyle_(versioningStyle),
         syncStartTime_(syncStartTime),
-        timeStamp_(zen::formatTime<Zstring>(Zstr("%Y-%m-%d %H%M%S"), zen::getLocalTime(syncStartTime))) //e.g. "2012-05-15 131513"
+        timeStamp_(zen::formatTime(Zstr("%Y-%m-%d %H%M%S"), zen::getLocalTime(syncStartTime))) //e.g. "2012-05-15 131513"
     {
         using namespace zen;
 
         if (AbstractFileSystem::isNullPath(versioningFolderPath_))
-            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
 
         if (timeStamp_.size() != 17) //formatTime() returns empty string on error; unexpected length: e.g. problem in year 10,000!
             throw FileError(_("Unable to create time stamp for versioning:") + L" \"" + utfTo<std::wstring>(timeStamp_) + L'"');
diff --git a/FreeFileSync/Source/base_tools.cpp b/FreeFileSync/Source/base_tools.cpp
new file mode 100644
index 00000000..3a7dabbd
--- /dev/null
+++ b/FreeFileSync/Source/base_tools.cpp
@@ -0,0 +1,357 @@
+// *****************************************************************************
+// * This file is part of the FreeFileSync project. It is distributed under    *
+// * GNU General Public License: https://www.gnu.org/licenses/gpl-3.0          *
+// * Copyright (C) Zenju (zenju AT freefilesync DOT org) - All Rights Reserved *
+// *****************************************************************************
+
+#include "base_tools.h"
+#include <wx/app.h>
+#include "base/path_filter.h"
+
+using namespace zen;
+using namespace fff;
+
+
+std::wstring fff::getVariantName(CompareVariant var)
+{
+    switch (var)
+    {
+        case CompareVariant::timeSize:
+            return _("File time and size");
+        case CompareVariant::content:
+            return _("File content");
+        case CompareVariant::size:
+            return _("File size");
+    }
+    assert(false);
+    return _("Error");
+}
+
+
+std::wstring fff::getVariantName(DirectionConfig::Variant var)
+{
+    const wchar_t* arrowLeft  = L"\u25C4 "; //black triangle pointer
+    const wchar_t* arrowRight = L" \u25BA"; //
+    const wchar_t* angleRight = L" \uFF1E"; //fullwidth greater-than
+    //const wchar_t arrowLeft [] = L"\u2190 "; //unicode arrows -> too small
+    //const wchar_t arrowRight[] = L" \u2192"; //
+
+    if (wxTheApp->GetLayoutDirection() == wxLayout_RightToLeft)
+    {
+        arrowLeft  = L"\u25BA "; //not mirrored automatically: Windows/Linux Unicode bug!?
+        arrowRight = L" \u25C4"; //
+    }
+    return getVariantNameImpl(var, arrowLeft, arrowRight, angleRight);
+}
+
+
+std::wstring fff::getCompVariantName(const MainConfiguration& mainCfg)
+{
+    const CompareVariant firstVariant = mainCfg.firstPair.localCmpCfg ?
+                                        mainCfg.firstPair.localCmpCfg->compareVar :
+                                        mainCfg.cmpCfg.compareVar; //fallback to main sync cfg
+
+    //test if there's a deviating variant within the additional folder pairs
+    for (const LocalPairConfig& lpc : mainCfg.additionalPairs)
+    {
+        const CompareVariant thisVariant = lpc.localCmpCfg ?
+                                           lpc.localCmpCfg->compareVar :
+                                           mainCfg.cmpCfg.compareVar; //fallback to main sync cfg
+        if (thisVariant != firstVariant)
+            return _("Multiple...");
+    }
+
+    //seems to be all in sync...
+    return getVariantName(firstVariant);
+}
+
+
+std::wstring fff::getSyncVariantName(const MainConfiguration& mainCfg)
+{
+    const DirectionConfig::Variant firstVariant = mainCfg.firstPair.localSyncCfg ?
+                                                  mainCfg.firstPair.localSyncCfg->directionCfg.var :
+                                                  mainCfg.syncCfg.directionCfg.var; //fallback to main sync cfg
+
+    //test if there's a deviating variant within the additional folder pairs
+    for (const LocalPairConfig& lpc : mainCfg.additionalPairs)
+    {
+        const DirectionConfig::Variant thisVariant = lpc.localSyncCfg ?
+                                                     lpc.localSyncCfg->directionCfg.var :
+                                                     mainCfg.syncCfg.directionCfg.var;
+        if (thisVariant != firstVariant)
+            return _("Multiple...");
+    }
+
+    //seems to be all in sync...
+    return getVariantName(firstVariant);
+}
+
+
+std::vector<unsigned int> fff::fromTimeShiftPhrase(const std::wstring& timeShiftPhrase)
+{
+    std::wstring tmp = replaceCpy(timeShiftPhrase, L';', L','); //harmonize , ; and ' '
+    replace(tmp, L' ', L',');                                   //
+    replace(tmp, L'-', L""); //there is no negative shift => treat as positive!
+
+    std::set<unsigned int> minutes;
+    for (const std::wstring& part : split(tmp, L',', SplitType::SKIP_EMPTY))
+    {
+        if (contains(part, L':'))
+            minutes.insert(stringTo<unsigned int>(beforeFirst(part, L':', IF_MISSING_RETURN_NONE)) * 60 +
+                           stringTo<unsigned int>(afterFirst (part, L':', IF_MISSING_RETURN_NONE)));
+        else
+            minutes.insert(stringTo<unsigned int>(part) * 60);
+    }
+    minutes.erase(0);
+
+    return { minutes.begin(), minutes.end() };
+}
+
+
+std::wstring fff::toTimeShiftPhrase(const std::vector<unsigned int>& ignoreTimeShiftMinutes)
+{
+    std::wstring phrase;
+    for (auto it = ignoreTimeShiftMinutes.begin(); it != ignoreTimeShiftMinutes.end(); ++it)
+    {
+        if (it != ignoreTimeShiftMinutes.begin())
+            phrase += L", ";
+
+        phrase += numberTo<std::wstring>(*it / 60);
+        if (*it % 60 != 0)
+            phrase += L':' + printNumber<std::wstring>(L"%02d", static_cast<int>(*it % 60));
+    }
+    return phrase;
+}
+
+
+void fff::logNonDefaultSettings(const XmlGlobalSettings& activeSettings, PhaseCallback& callback)
+{
+    const XmlGlobalSettings defaultSettings;
+    std::wstring changedSettingsMsg;
+
+    if (activeSettings.failSafeFileCopy != defaultSettings.failSafeFileCopy)
+        changedSettingsMsg += L"\n    " + _("Fail-safe file copy") + L" - " + (activeSettings.failSafeFileCopy ? _("Enabled") : _("Disabled"));
+
+    if (activeSettings.copyLockedFiles != defaultSettings.copyLockedFiles)
+        changedSettingsMsg += L"\n    " + _("Copy locked files") + L" - " + (activeSettings.copyLockedFiles ? _("Enabled") : _("Disabled"));
+
+    if (activeSettings.copyFilePermissions != defaultSettings.copyFilePermissions)
+        changedSettingsMsg += L"\n    " + _("Copy file access permissions") + L" - " + (activeSettings.copyFilePermissions ? _("Enabled") : _("Disabled"));
+
+    if (activeSettings.fileTimeTolerance != defaultSettings.fileTimeTolerance)
+        changedSettingsMsg += L"\n    " + _("File time tolerance") + L" - " + numberTo<std::wstring>(activeSettings.fileTimeTolerance);
+
+    if (activeSettings.runWithBackgroundPriority != defaultSettings.runWithBackgroundPriority)
+        changedSettingsMsg += L"\n    " + _("Run with background priority") + L" - " + (activeSettings.runWithBackgroundPriority ? _("Enabled") : _("Disabled"));
+
+    if (activeSettings.createLockFile != defaultSettings.createLockFile)
+        changedSettingsMsg += L"\n    " + _("Lock directories during sync") + L" - " + (activeSettings.createLockFile ? _("Enabled") : _("Disabled"));
+
+    if (activeSettings.verifyFileCopy != defaultSettings.verifyFileCopy)
+        changedSettingsMsg += L"\n    " + _("Verify copied files") + L" - " + (activeSettings.verifyFileCopy ? _("Enabled") : _("Disabled"));
+
+    if (!changedSettingsMsg.empty())
+        callback.reportInfo(_("Using non-default global settings:") + changedSettingsMsg); //throw X
+}
+
+
+namespace
+{
+FilterConfig mergeFilterConfig(const FilterConfig& global, const FilterConfig& local)
+{
+    FilterConfig out = local;
+
+    //hard filter
+    if (NameFilter::isNull(local.includeFilter, Zstring())) //fancy way of checking for "*" include
+        out.includeFilter = global.includeFilter;
+    //else : if both global and local include filters are set, only local filter is preserved
+
+    out.excludeFilter = trimCpy(trimCpy(global.excludeFilter) + Zstr("\n\n") + trimCpy(local.excludeFilter));
+
+    //soft filter
+    time_t   loctimeFrom  = 0;
+    uint64_t locSizeMinBy = 0;
+    uint64_t locSizeMaxBy = 0;
+    resolveUnits(out.timeSpan, out.unitTimeSpan,
+                 out.sizeMin,  out.unitSizeMin,
+                 out.sizeMax,  out.unitSizeMax,
+                 loctimeFrom,   //unit: UTC time, seconds
+                 locSizeMinBy,  //unit: bytes
+                 locSizeMaxBy); //unit: bytes
+
+    //soft filter
+    time_t   glotimeFrom  = 0;
+    uint64_t gloSizeMinBy = 0;
+    uint64_t gloSizeMaxBy = 0;
+    resolveUnits(global.timeSpan, global.unitTimeSpan,
+                 global.sizeMin,  global.unitSizeMin,
+                 global.sizeMax,  global.unitSizeMax,
+                 glotimeFrom,
+                 gloSizeMinBy,
+                 gloSizeMaxBy);
+
+    if (glotimeFrom > loctimeFrom)
+    {
+        out.timeSpan     = global.timeSpan;
+        out.unitTimeSpan = global.unitTimeSpan;
+    }
+    if (gloSizeMinBy > locSizeMinBy)
+    {
+        out.sizeMin     = global.sizeMin;
+        out.unitSizeMin = global.unitSizeMin;
+    }
+    if (gloSizeMaxBy < locSizeMaxBy)
+    {
+        out.sizeMax     = global.sizeMax;
+        out.unitSizeMax = global.unitSizeMax;
+    }
+    return out;
+}
+
+
+inline
+bool effectivelyEmpty(const LocalPairConfig& lpc)
+{
+    return trimCpy(lpc.folderPathPhraseLeft ).empty() &&
+           trimCpy(lpc.folderPathPhraseRight).empty();
+}
+}
+
+
+MainConfiguration fff::merge(const std::vector<MainConfiguration>& mainCfgs)
+{
+    assert(!mainCfgs.empty());
+    if (mainCfgs.empty())
+        return MainConfiguration();
+
+    if (mainCfgs.size() == 1) //mergeConfigFilesImpl relies on this!
+        return mainCfgs[0];   //
+
+    //merge folder pair config
+    std::vector<LocalPairConfig> mergedCfgs;
+    for (const MainConfiguration& mainCfg : mainCfgs)
+    {
+        std::vector<LocalPairConfig> tmpCfgs;
+
+        //skip empty folder pairs
+        if (!effectivelyEmpty(mainCfg.firstPair))
+            tmpCfgs.push_back(mainCfg.firstPair);
+
+        for (const LocalPairConfig& lpc : mainCfg.additionalPairs)
+            if (!effectivelyEmpty(lpc))
+                tmpCfgs.push_back(lpc);
+
+        //move all configuration down to item level
+        for (LocalPairConfig& lpc : tmpCfgs)
+        {
+            if (!lpc.localCmpCfg)
+                lpc.localCmpCfg = mainCfg.cmpCfg;
+
+            if (!lpc.localSyncCfg)
+                lpc.localSyncCfg = mainCfg.syncCfg;
+
+            lpc.localFilter = mergeFilterConfig(mainCfg.globalFilter, lpc.localFilter);
+        }
+        append(mergedCfgs, tmpCfgs);
+    }
+
+    if (mergedCfgs.empty())
+        return MainConfiguration();
+
+    //optimization: remove redundant configuration
+
+    //########################################################################################################################
+    //find out which comparison and synchronization setting are used most often and use them as new "header"
+    std::vector<std::pair<CompConfig, int>> cmpCfgStat;
+    std::vector<std::pair<SyncConfig, int>> syncCfgStat;
+    for (const LocalPairConfig& lpc : mergedCfgs)
+    {
+        //a rather inefficient algorithm, but it does not require a less-than operator:
+        {
+            const CompConfig& cmpCfg = *lpc.localCmpCfg;
+
+            auto it = std::find_if(cmpCfgStat.begin(), cmpCfgStat.end(),
+            [&](const std::pair<CompConfig, int>& entry) { return effectivelyEqual(entry.first, cmpCfg); });
+            if (it == cmpCfgStat.end())
+                cmpCfgStat.emplace_back(cmpCfg, 1);
+            else
+                ++(it->second);
+        }
+        {
+            const SyncConfig& syncCfg = *lpc.localSyncCfg;
+
+            auto it = std::find_if(syncCfgStat.begin(), syncCfgStat.end(),
+            [&](const std::pair<SyncConfig, int>& entry) { return effectivelyEqual(entry.first, syncCfg); });
+            if (it == syncCfgStat.end())
+                syncCfgStat.emplace_back(syncCfg, 1);
+            else
+                ++(it->second);
+        }
+    }
+
+    //set most-used comparison and synchronization settings as new header options
+    const CompConfig cmpCfgHead = cmpCfgStat.empty() ? CompConfig() :
+                                  std::max_element(cmpCfgStat.begin(), cmpCfgStat.end(),
+    [](const std::pair<CompConfig, int>& lhs, const std::pair<CompConfig, int>& rhs) { return lhs.second < rhs.second; })->first;
+
+    const SyncConfig syncCfgHead = syncCfgStat.empty() ? SyncConfig() :
+                                   std::max_element(syncCfgStat.begin(), syncCfgStat.end(),
+    [](const std::pair<SyncConfig, int>& lhs, const std::pair<SyncConfig, int>& rhs) { return lhs.second < rhs.second; })->first;
+    //########################################################################################################################
+
+    FilterConfig globalFilter;
+    const bool allFiltersEqual = std::all_of(mergedCfgs.begin(), mergedCfgs.end(), [&](const LocalPairConfig& lpc) { return lpc.localFilter == mergedCfgs[0].localFilter; });
+    if (allFiltersEqual)
+        globalFilter = mergedCfgs[0].localFilter;
+
+    //strip redundancy...
+    for (LocalPairConfig& lpc : mergedCfgs)
+    {
+        //if local config matches output global config we don't need local one
+        if (lpc.localCmpCfg &&
+            effectivelyEqual(*lpc.localCmpCfg, cmpCfgHead))
+            lpc.localCmpCfg = {};
+
+        if (lpc.localSyncCfg &&
+            effectivelyEqual(*lpc.localSyncCfg, syncCfgHead))
+            lpc.localSyncCfg = {};
+
+        if (allFiltersEqual) //use global filter in this case
+            lpc.localFilter = FilterConfig();
+    }
+
+    std::map<AfsDevice, size_t> mergedParallelOps;
+    for (const MainConfiguration& mainCfg : mainCfgs)
+        for (const auto& [rootPath, parallelOps] : mainCfg.deviceParallelOps)
+            mergedParallelOps[rootPath] = std::max(mergedParallelOps[rootPath], parallelOps);
+
+    //final assembly
+    MainConfiguration cfgOut;
+    cfgOut.cmpCfg       = cmpCfgHead;
+    cfgOut.syncCfg      = syncCfgHead;
+    cfgOut.globalFilter = globalFilter;
+    cfgOut.firstPair    = mergedCfgs[0];
+    cfgOut.additionalPairs.assign(mergedCfgs.begin() + 1, mergedCfgs.end());
+    cfgOut.deviceParallelOps = mergedParallelOps;
+
+    cfgOut.ignoreErrors = std::all_of(mainCfgs.begin(), mainCfgs.end(), [](const MainConfiguration& mainCfg) { return mainCfg.ignoreErrors; });
+
+    cfgOut.automaticRetryCount = std::max_element(mainCfgs.begin(), mainCfgs.end(),
+    [](const MainConfiguration& lhs, const MainConfiguration& rhs) { return lhs.automaticRetryCount < rhs.automaticRetryCount; })->automaticRetryCount;
+
+    cfgOut.automaticRetryDelay = std::max_element(mainCfgs.begin(), mainCfgs.end(),
+    [](const MainConfiguration& lhs, const MainConfiguration& rhs) { return lhs.automaticRetryDelay < rhs.automaticRetryDelay; })->automaticRetryDelay;
+
+    for (const MainConfiguration& mainCfg : mainCfgs)
+        if (!mainCfg.altLogFolderPathPhrase.empty())
+        {
+            cfgOut.altLogFolderPathPhrase = mainCfg.altLogFolderPathPhrase;
+            break;
+        }
+
+    //cfgOut.postSyncCommand   = -> better leave at default ... !?
+    //cfgOut.postSyncCondition = ->
+    //cfgOut.emailNotifyAddress   = -> better leave at default ... !?
+    //cfgOut.emailNotifyCondition = ->
+    return cfgOut;
+}
diff --git a/FreeFileSync/Source/base_tools.h b/FreeFileSync/Source/base_tools.h
new file mode 100644
index 00000000..e5ad9a2f
--- /dev/null
+++ b/FreeFileSync/Source/base_tools.h
@@ -0,0 +1,33 @@
+// *****************************************************************************
+// * This file is part of the FreeFileSync project. It is distributed under    *
+// * GNU General Public License: https://www.gnu.org/licenses/gpl-3.0          *
+// * Copyright (C) Zenju (zenju AT freefilesync DOT org) - All Rights Reserved *
+// *****************************************************************************
+
+#ifndef STRUCTURE_TOOLS_H_7823097420397434
+#define STRUCTURE_TOOLS_H_7823097420397434
+
+#include "base/structures.h"
+#include "base/process_callback.h"
+#include "config.h"
+
+
+namespace fff
+{
+std::wstring getVariantName(CompareVariant var);
+std::wstring getVariantName(DirectionConfig::Variant var);
+std::wstring getCompVariantName(const MainConfiguration& mainCfg);
+std::wstring getSyncVariantName(const MainConfiguration& mainCfg);
+
+//convert "ignoreTimeShiftMinutes" into compact format:
+std::vector<unsigned int> fromTimeShiftPhrase(const std::wstring& timeShiftPhrase);
+std::wstring              toTimeShiftPhrase  (const std::vector<unsigned int>& ignoreTimeShiftMinutes);
+
+//inform about (important) non-default global settings related to comparison and synchronization
+void logNonDefaultSettings(const XmlGlobalSettings& currentSettings, PhaseCallback& callback);
+
+//facilitate drag & drop config merge:
+MainConfiguration merge(const std::vector<MainConfiguration>& mainCfgs);
+}
+
+#endif //STRUCTURE_TOOLS_H_7823097420397434
diff --git a/FreeFileSync/Source/base/config.cpp b/FreeFileSync/Source/config.cpp
index 0a170bbb..120ad466 100644
--- a/FreeFileSync/Source/base/config.cpp
+++ b/FreeFileSync/Source/config.cpp
@@ -11,7 +11,7 @@
 #include <zen/time.h>
 #include <wx/intl.h>
 #include "ffs_paths.h"
-//#include "../afs/concrete.h"
+#include "base_tools.h"
 
 
 using namespace zen;
@@ -662,6 +662,35 @@ bool readText(const std::string& input, UnitTime& value)
     return true;
 }
 
+
+template <> inline
+void writeText(const LogFileFormat& value, std::string& output)
+{
+    switch (value)
+    {
+        case LogFileFormat::html:
+            output = "HTML";
+            break;
+        case LogFileFormat::text:
+            output = "Text";
+            break;
+    }
+}
+
+template <> inline
+bool readText(const std::string& input, LogFileFormat& value)
+{
+    const std::string tmp = trimCpy(input);
+    if (tmp == "HTML")
+        value = LogFileFormat::html;
+    else if (tmp == "Text")
+        value = LogFileFormat::text;
+    else
+        return false;
+    return true;
+}
+
+
 template <> inline
 void writeText(const VersioningStyle& value, std::string& output)
 {
@@ -1092,8 +1121,8 @@ void readConfig(const XmlIn& in, SyncConfig& syncCfg, std::map<AfsDevice, size_t
 
         if (syncCfg.versioningStyle == VersioningStyle::replace)
         {
-            if (endsWithAsciiNoCase(syncCfg.versioningFolderPhrase, Zstr("/%timestamp%")) ||
-                endsWithAsciiNoCase(syncCfg.versioningFolderPhrase, Zstr("\\%timestamp%")))
+            if (endsWithAsciiNoCase(syncCfg.versioningFolderPhrase, "/%timestamp%") ||
+                endsWithAsciiNoCase(syncCfg.versioningFolderPhrase, "\\%timestamp%"))
             {
                 syncCfg.versioningFolderPhrase.resize(syncCfg.versioningFolderPhrase.size() - strLength(Zstr("/%timestamp%")));
                 syncCfg.versioningStyle = VersioningStyle::timestampFolder;
@@ -1173,8 +1202,8 @@ void readConfig(const XmlIn& in, LocalPairConfig& lpc, std::map<AfsDevice, size_
     {
         auto getParallelOps = [&](const Zstring& folderPathPhrase, size_t& parallelOps)
         {
-            if (startsWithAsciiNoCase(folderPathPhrase, Zstr("sftp:")) ||
-                startsWithAsciiNoCase(folderPathPhrase, Zstr( "ftp:")))
+            if (startsWithAsciiNoCase(folderPathPhrase, "sftp:") ||
+                startsWithAsciiNoCase(folderPathPhrase,  "ftp:"))
             {
                 for (const Zstring& optPhrase : split(folderPathPhrase, Zstr("|"), SplitType::SKIP_EMPTY))
                     if (startsWith(optPhrase, Zstr("con=")))
@@ -1481,6 +1510,7 @@ void readConfig(const XmlIn& in, XmlGlobalSettings& cfg, int formatVer)
     inGeneral["LockDirectoriesDuringSync"].attribute("Enabled", cfg.createLockFile);
     inGeneral["VerifyCopiedFiles"        ].attribute("Enabled", cfg.verifyFileCopy);
     inGeneral["LogFiles"                 ].attribute("MaxAge",  cfg.logfilesMaxAgeDays);
+    inGeneral["LogFiles"                 ].attribute("Format",  cfg.logFormat);
     inGeneral["NotificationSound"        ].attribute("CompareFinished", cfg.soundFileCompareFinished);
     inGeneral["NotificationSound"        ].attribute("SyncFinished",    cfg.soundFileSyncFinished);
     inGeneral["ProgressDialog"           ].attribute("AutoClose",       cfg.autoCloseProgressDialog);
@@ -2205,6 +2235,7 @@ void writeConfig(const XmlGlobalSettings& cfg, XmlOut& out)
     outGeneral["LockDirectoriesDuringSync"].attribute("Enabled", cfg.createLockFile);
     outGeneral["VerifyCopiedFiles"        ].attribute("Enabled", cfg.verifyFileCopy);
     outGeneral["LogFiles"                 ].attribute("MaxAge",  cfg.logfilesMaxAgeDays);
+    outGeneral["LogFiles"                 ].attribute("Format",  cfg.logFormat);
     outGeneral["NotificationSound"        ].attribute("CompareFinished", substituteFfsResourcePath(cfg.soundFileCompareFinished));
     outGeneral["NotificationSound"        ].attribute("SyncFinished",    substituteFfsResourcePath(cfg.soundFileSyncFinished));
     outGeneral["ProgressDialog"           ].attribute("AutoClose",       cfg.autoCloseProgressDialog);
diff --git a/FreeFileSync/Source/base/config.h b/FreeFileSync/Source/config.h
index dcafb207..e76d4770 100644
--- a/FreeFileSync/Source/base/config.h
+++ b/FreeFileSync/Source/config.h
@@ -9,10 +9,11 @@
 
 #include <wx/gdicmn.h>
 #include "localization.h"
-#include "structures.h"
-#include "../ui/file_grid_attr.h"
-#include "../ui/tree_grid_attr.h" //RTS: avoid tree grid's "file_hierarchy.h" dependency!
-#include "../ui/cfg_grid.h"
+#include "base/structures.h"
+#include "ui/file_grid_attr.h"
+#include "ui/tree_grid_attr.h" //RTS: avoid tree grid's "file_hierarchy.h" dependency!
+#include "ui/cfg_grid.h"
+#include "log_file.h"
 
 
 namespace fff
@@ -95,40 +96,6 @@ inline bool operator==(const ConfirmationDialogs& lhs, const ConfirmationDialogs
 inline bool operator!=(const ConfirmationDialogs& lhs, const ConfirmationDialogs& rhs) { return !(lhs == rhs); }
 
 
-struct WarningDialogs
-{
-    bool warnFolderNotExisting          = true;
-    bool warnFoldersDifferInCase        = true;
-    bool warnDependentFolderPair        = true;
-    bool warnDependentBaseFolders       = true;
-    bool warnSignificantDifference      = true;
-    bool warnNotEnoughDiskSpace         = true;
-    bool warnUnresolvedConflicts        = true;
-    bool warnModificationTimeError      = true;
-    bool warnRecyclerMissing            = true;
-    bool warnInputFieldEmpty            = true;
-    bool warnDirectoryLockFailed        = true;
-    bool warnVersioningFolderPartOfSync = true;
-};
-inline bool operator==(const WarningDialogs& lhs, const WarningDialogs& rhs)
-{
-    return lhs.warnFolderNotExisting          == rhs.warnFolderNotExisting     &&
-           lhs.warnFoldersDifferInCase        == rhs.warnFoldersDifferInCase   &&
-           lhs.warnDependentFolderPair        == rhs.warnDependentFolderPair   &&
-           lhs.warnDependentBaseFolders       == rhs.warnDependentBaseFolders  &&
-           lhs.warnSignificantDifference      == rhs.warnSignificantDifference &&
-           lhs.warnNotEnoughDiskSpace         == rhs.warnNotEnoughDiskSpace    &&
-           lhs.warnUnresolvedConflicts        == rhs.warnUnresolvedConflicts   &&
-           lhs.warnModificationTimeError      == rhs.warnModificationTimeError &&
-           lhs.warnRecyclerMissing            == rhs.warnRecyclerMissing       &&
-           lhs.warnInputFieldEmpty            == rhs.warnInputFieldEmpty       &&
-           lhs.warnDirectoryLockFailed        == rhs.warnDirectoryLockFailed   &&
-           lhs.warnVersioningFolderPartOfSync == rhs.warnVersioningFolderPartOfSync;
-}
-inline bool operator!=(const WarningDialogs& lhs, const WarningDialogs& rhs) { return !(lhs == rhs); }
-
-
-
 enum class FileIconSize
 {
     SMALL,
@@ -179,6 +146,7 @@ struct XmlGlobalSettings
     bool createLockFile = true;
     bool verifyFileCopy = false;
     int logfilesMaxAgeDays = 30; //<= 0 := no limit; for log files under %AppData%\FreeFileSync\Logs
+    LogFileFormat logFormat = LogFileFormat::html;
 
     Zstring soundFileCompareFinished;
     Zstring soundFileSyncFinished;
@@ -238,8 +206,8 @@ struct XmlGlobalSettings
             wxString guiPerspectiveLast; //used by wxAuiManager
         } mainDlg;
 
-        Zstring defaultExclusionFilter = Zstr("/.Trash-*/") Zstr("\n")
-                                         Zstr("/.recycle/");
+        Zstring defaultExclusionFilter = "/.Trash-*/" "\n"
+                                         "/.recycle/";
         size_t folderHistoryMax = 20;
 
         std::vector<Zstring> versioningFolderHistory;
diff --git a/FreeFileSync/Source/base/fatal_error.h b/FreeFileSync/Source/fatal_error.h
index a27e423b..84ceb6dc 100644
--- a/FreeFileSync/Source/base/fatal_error.h
+++ b/FreeFileSync/Source/fatal_error.h
@@ -33,7 +33,7 @@ void logFatalError(const std::string& msg) //noexcept
     using namespace zen;
 
     assert(false); //this is stuff we like to debug
-    const std::string logEntry = "[" + formatTime<std::string>(FORMAT_DATE) + " " + formatTime<std::string>(FORMAT_TIME) + "] " + msg;
+    const std::string logEntry = '[' + utfTo<std::string>(formatTime(formatDateTag) + Zstr(' ') + formatTime(formatTimeTag)) + "] " + msg;
     try
     {
         saveBinContainer(getConfigDirPathPf() + Zstr("LastError.log"), logEntry, nullptr /*notifyUnbufferedIO*/); //throw FileError
diff --git a/FreeFileSync/Source/base/ffs_paths.cpp b/FreeFileSync/Source/ffs_paths.cpp
index 843e702e..843e702e 100644
--- a/FreeFileSync/Source/base/ffs_paths.cpp
+++ b/FreeFileSync/Source/ffs_paths.cpp
diff --git a/FreeFileSync/Source/base/ffs_paths.h b/FreeFileSync/Source/ffs_paths.h
index bf103e28..bf103e28 100644
--- a/FreeFileSync/Source/base/ffs_paths.h
+++ b/FreeFileSync/Source/ffs_paths.h
diff --git a/FreeFileSync/Source/base/help_provider.h b/FreeFileSync/Source/help_provider.h
index d9a1b3fc..d9a1b3fc 100644
--- a/FreeFileSync/Source/base/help_provider.h
+++ b/FreeFileSync/Source/help_provider.h
diff --git a/FreeFileSync/Source/base/icon_buffer.cpp b/FreeFileSync/Source/icon_buffer.cpp
index b10027a6..4b032bd3 100644
--- a/FreeFileSync/Source/base/icon_buffer.cpp
+++ b/FreeFileSync/Source/icon_buffer.cpp
@@ -11,7 +11,7 @@
 #include <zen/scope_guard.h>
 #include <wx+/image_resources.h>
 #include <wx+/dc.h>
-#include "icon_loader.h"
+#include "base/icon_loader.h"
 
 
 using namespace zen;
diff --git a/FreeFileSync/Source/base/icon_buffer.h b/FreeFileSync/Source/icon_buffer.h
index d6dd504f..b5ce9eae 100644
--- a/FreeFileSync/Source/base/icon_buffer.h
+++ b/FreeFileSync/Source/icon_buffer.h
@@ -11,7 +11,7 @@
 #include <memory>
 #include <zen/zstring.h>
 #include <wx/bitmap.h>
-#include "../afs/abstract.h"
+#include "afs/abstract.h"
 
 
 namespace fff
diff --git a/FreeFileSync/Source/base/localization.cpp b/FreeFileSync/Source/localization.cpp
index ef1ee778..ef1ee778 100644
--- a/FreeFileSync/Source/base/localization.cpp
+++ b/FreeFileSync/Source/localization.cpp
diff --git a/FreeFileSync/Source/base/localization.h b/FreeFileSync/Source/localization.h
index e635ac1e..e635ac1e 100644
--- a/FreeFileSync/Source/base/localization.h
+++ b/FreeFileSync/Source/localization.h
diff --git a/FreeFileSync/Source/base/log_file.cpp b/FreeFileSync/Source/log_file.cpp
index ac866e9a..b7032137 100644
--- a/FreeFileSync/Source/base/log_file.cpp
+++ b/FreeFileSync/Source/log_file.cpp
@@ -10,7 +10,7 @@
 #include <zen/system.h>
 #include <wx/datetime.h>
 #include "ffs_paths.h"
-#include "../afs/concrete.h"
+#include "afs/concrete.h"
 
 using namespace zen;
 using namespace fff;
@@ -35,21 +35,20 @@ std::string generateLogHeaderTxt(const ProcessSummary& s, const ErrorLog& log, i
         headerLine += "  ";
 
     const TimeComp tc = getLocalTime(std::chrono::system_clock::to_time_t(s.startTime)); //returns empty string on failure
-    headerLine += formatTime<std::string>(FORMAT_DATE, tc) + " [" + formatTime<std::string>(FORMAT_TIME, tc) + ']';
+    headerLine += utfTo<std::string>(formatTime(formatDateTag, tc) + Zstr(" [") + formatTime(formatTimeTag, tc) + Zstr(']'));
 
     //assemble summary box
     std::vector<std::string> summary;
     summary.emplace_back();
-    summary.push_back(tabSpace + utfTo<std::string>(getResultsStatusLabel(s.resultStatus)));
+    summary.push_back(tabSpace + utfTo<std::string>(getSyncResultLabel(s.resultStatus)));
     summary.emplace_back();
 
-    const int errorCount   = log.getItemCount(MSG_TYPE_ERROR | MSG_TYPE_FATAL_ERROR);
-    const int warningCount = log.getItemCount(MSG_TYPE_WARNING);
+    const ErrorLog::Stats logCount = log.getStats();
 
-    if (errorCount   > 0) summary.push_back(tabSpace + utfTo<std::string>(_("Errors:")   + L" " + formatNumber(errorCount)));
-    if (warningCount > 0) summary.push_back(tabSpace + utfTo<std::string>(_("Warnings:") + L" " + formatNumber(warningCount)));
+    if (logCount.error + logCount.fatal > 0) summary.push_back(tabSpace + utfTo<std::string>(_("Errors:")   + L' ' + formatNumber(logCount.error + logCount.fatal)));
+    if (logCount.warning                > 0) summary.push_back(tabSpace + utfTo<std::string>(_("Warnings:") + L' ' + formatNumber(logCount.warning)));
 
-    summary.push_back(tabSpace + utfTo<std::string>(_("Items processed:") + L" " + formatNumber(s.statsProcessed.items) + //show always, even if 0!
+    summary.push_back(tabSpace + utfTo<std::string>(_("Items processed:") + L' ' + formatNumber(s.statsProcessed.items) + //show always, even if 0!
                                                     L" (" + formatFilesizeShort(s.statsProcessed.bytes) + L')'));
 
     if ((s.statsTotal.items < 0 && s.statsTotal.bytes < 0) || //no total items/bytes: e.g. for pure folder comparison
@@ -57,11 +56,11 @@ std::string generateLogHeaderTxt(const ProcessSummary& s, const ErrorLog& log, i
         ;
     else
         summary.push_back(tabSpace + utfTo<std::string>(_("Items remaining:") +
-                                                        L" "  + formatNumber       (s.statsTotal.items - s.statsProcessed.items) +
+                                                        L' '  + formatNumber       (s.statsTotal.items - s.statsProcessed.items) +
                                                         L" (" + formatFilesizeShort(s.statsTotal.bytes - s.statsProcessed.bytes) + L')'));
 
     const int64_t totalTimeSec = std::chrono::duration_cast<std::chrono::seconds>(s.totalTime).count();
-    summary.push_back(tabSpace + utfTo<std::string>(_("Total time:")) + " " + utfTo<std::string>(wxTimeSpan::Seconds(totalTimeSec).Format()));
+    summary.push_back(tabSpace + utfTo<std::string>(_("Total time:")) + ' ' + utfTo<std::string>(wxTimeSpan::Seconds(totalTimeSec).Format()));
 
     size_t sepLineLen = 0; //calculate max width (considering Unicode!)
     for (const std::string& str : summary) sepLineLen = std::max(sepLineLen, unicodeLength(str));
@@ -75,20 +74,21 @@ std::string generateLogHeaderTxt(const ProcessSummary& s, const ErrorLog& log, i
     output += '|' + std::string(sepLineLen, '_') + "\n\n";
 
     //------------ warnings/errors preview ----------------
-    const int logFailTotal = errorCount + warningCount;
+    const int logFailTotal = logCount.warning + logCount.error + logCount.fatal;
     if (logFailTotal > 0)
     {
         output += '\n' + utfTo<std::string>(_("Errors and warnings:")) + '\n';
         output += std::string(SEPARATION_LINE_LEN, '_') + '\n';
 
         int previewCount = 0;
-        for (const LogEntry& entry : log)
-            if (entry.type & (MSG_TYPE_WARNING | MSG_TYPE_ERROR | MSG_TYPE_FATAL_ERROR))
-            {
-                output += utfTo<std::string>(formatMessage(entry));
-                if (++previewCount >= logFailsPreviewMax)
-                    break;
-            }
+        if (logFailsPreviewMax > 0)
+            for (const LogEntry& entry : log)
+                if (entry.type & (MSG_TYPE_WARNING | MSG_TYPE_ERROR | MSG_TYPE_FATAL_ERROR))
+                {
+                    output += utfTo<std::string>(formatMessage(entry));
+                    if (++previewCount >= logFailsPreviewMax)
+                        break;
+                }
         if (logFailTotal > previewCount)
             output += "  [...]  " + utfTo<std::string>(replaceCpy(_P("Showing %y of 1 row", "Showing %y of %x rows", logFailTotal), //%x used as plural form placeholder!
                                                                   L"%y", formatNumber(previewCount))) + '\n';
@@ -107,17 +107,21 @@ std::string generateLogFooterTxt(const std::wstring& logFilePath, int logItemsTo
         output += "  [...]  " + utfTo<std::string>(replaceCpy(_P("Showing %y of 1 row", "Showing %y of %x rows", logItemsTotal), //%x used as plural form placeholder!
                                                               L"%y", formatNumber(logItemsPreviewMax))) + '\n';
 
-    return output += '\n' + utfTo<std::string>(getOsDescription() + /*throw FileError*/ +
-                                               L" [" +  getUserName() /*throw FileError*/ + L"] - " + cm.model + L" - " + cm.vendor + L'\n' +
-                                               std::wstring(SEPARATION_LINE_LEN, L'_') + L'\n' +
-                                               _("Log file") + L": " + logFilePath) + '\n';
+    return output += '\n' + std::string(SEPARATION_LINE_LEN, '_') + '\n' +
+
+                     utfTo<std::string>(getOsDescription() + /*throw FileError*/ +
+                                        L" [" +  getUserName() /*throw FileError*/ + L']' +
+                                        (!cm.model .empty() ? L" - " + cm.model  : L"") +
+                                        (!cm.vendor.empty() ? L" - " + cm.vendor : L"") + L'\n' +
+
+                                        _("Log file") + L": " + logFilePath) + '\n';
 }
 
 
-std::string htmlTxtImpl(std::string&& str)
+std::string htmlTxt(const std::string_view& str)
 {
-    trim(str);
     std::string msg = htmlSpecialChars(str);
+    trim(msg);
     if (!contains(msg, '\n'))
         return msg;
 
@@ -142,8 +146,9 @@ std::string htmlTxtImpl(std::string&& str)
     return msgFmt;
 }
 
-std::string htmlTxt(const std::wstring& str) { return htmlTxtImpl(utfTo<std::string>(str)); }
-std::string htmlTxt(const      wchar_t* str) { return htmlTxtImpl(utfTo<std::string>(str)); }
+std::string htmlTxt(const      Zstring& str) { return htmlTxt(utfTo<std::string>(str)); }
+std::string htmlTxt(const std::wstring& str) { return htmlTxt(utfTo<std::string>(str)); }
+std::string htmlTxt(const      wchar_t* str) { return htmlTxt(utfTo<std::string>(str)); }
 
 
 //Astyle screws up royally with the following raw string literals!
@@ -161,9 +166,9 @@ std::string formatMessageHtml(const LogEntry& entry)
     }
 
     return R"(		<tr>
-			<td valign="top">)" + formatTime<std::string>(FORMAT_TIME, getLocalTime(entry.time)) + R"(</td>
-			<td valign="top"><img src="https://freefilesync.org/images/log/)" + typeImage + R"(" width="16" height="16" alt=")" + typeLabel + R"(:" title=")" + typeLabel + R"("></td>
-			<td>)" + htmlTxt(entry.message.c_str()) + R"(</td>
+			<td valign="top">)" + htmlTxt(formatTime(formatTimeTag, getLocalTime(entry.time))) + R"(</td>
+			<td valign="top"><img src="https://freefilesync.org/images/log/)" + typeImage + R"(" height="16" alt=")" + typeLabel + R"(:"></td>
+			<td>)" + htmlTxt(makeStringView(entry.message.begin(), entry.message.end())) + R"(</td>
 		</tr>
 )";
 }
@@ -182,10 +187,10 @@ std::wstring generateLogTitle(const ProcessSummary& s)
 
     switch (s.resultStatus)
     {
-        case SyncResult::finishedSuccess: title += utfTo<std::wstring>("\xe2\x9c\x94\xef\xb8\x8f"); break;
-        case SyncResult::finishedWarning: title += utfTo<std::wstring>("\xe2\x9a\xa0"); break;
-        case SyncResult::finishedError:
-        case SyncResult::aborted:         title += utfTo<std::wstring>("\xe2\x9d\x8c"); break;
+        case SyncResult::finishedSuccess: title += utfTo<std::wstring>("\xe2\x9c\x94" "\xef\xb8\x8f"); break; //✔️
+        case SyncResult::finishedWarning: title += utfTo<std::wstring>("\xe2\x9a\xa0" "\xef\xb8\x8f"); break; //⚠️
+        case SyncResult::finishedError: //efb88f (U+FE0F): variation selector-16 to prefer emoji over text rendering
+        case SyncResult::aborted:         title += utfTo<std::wstring>("\xe2\x9d\x8c" "\xef\xb8\x8f"); break; //❌️
     }
     return title;
 }
@@ -207,7 +212,7 @@ std::string generateLogHeaderHtml(const ProcessSummary& s, const ErrorLog& log,
 
         .log-items img { display: block; }
 		.log-items td { padding-bottom: 0.1em; }
-		.log-items td:nth-child(1) { padding-right: 10px; }
+		.log-items td:nth-child(1) { padding-right: 10px; white-space: nowrap; }
 		.log-items td:nth-child(2) { padding-right: 10px; }
 	</style>
 </head>
@@ -220,7 +225,7 @@ std::string generateLogHeaderHtml(const ProcessSummary& s, const ErrorLog& log,
 
     const TimeComp tc = getLocalTime(std::chrono::system_clock::to_time_t(s.startTime)); //returns empty string on failure
     output += R"(	<div><span style="font-weight:600; color:gray;">)" + jobNamesFmt + R"(</span> &nbsp;<span style="white-space:nowrap">)" +
-              formatTime<std::string>(FORMAT_DATE, tc) + " &nbsp;" + formatTime<std::string>(FORMAT_TIME, tc) + "</span></div>\n";
+              htmlTxt(formatTime(formatDateTag, tc)) + " &nbsp;" + htmlTxt(formatTime(formatTimeTag, tc)) + "</span></div>\n";
 
     std::string resultsStatusImage;
     switch (s.resultStatus)
@@ -234,27 +239,26 @@ std::string generateLogHeaderHtml(const ProcessSummary& s, const ErrorLog& log,
 	<div style="margin:10px 0; display:inline-block; border-radius:7px; background:#f8f8f8; box-shadow:1px 1px 4px #888; overflow:hidden;">
 		<div style="background-color:white; border-bottom:1px solid #AAA; font-size:larger; padding:10px;">
 			<img src="https://freefilesync.org/images/log/)" + resultsStatusImage + R"(" width="32" height="32" alt="" style="vertical-align:middle;">
-			<span style="font-weight:600; vertical-align:middle;">)" + htmlTxt(getResultsStatusLabel(s.resultStatus)) + R"(</span>
+			<span style="font-weight:600; vertical-align:middle;">)" + htmlTxt(getSyncResultLabel(s.resultStatus)) + R"(</span>
 		</div>
 		<table role="presentation" class="summary-table" style="border-spacing:0; margin-left:10px; padding:5px 10px;">)";
 
-    const int errorCount   = log.getItemCount(MSG_TYPE_ERROR | MSG_TYPE_FATAL_ERROR);
-    const int warningCount = log.getItemCount(MSG_TYPE_WARNING);
+    const ErrorLog::Stats logCount = log.getStats();
 
-    if (errorCount > 0) 
+    if (logCount.error + logCount.fatal > 0) 
         output += R"(
 			<tr>
 				<td>)" + htmlTxt(_("Errors:")) + R"(</td>
 				<td><img src="https://freefilesync.org/images/log/msg-error.png" width="24" height="24" alt=""></td>
-				<td><span style="font-weight:600;">)" + htmlTxt(formatNumber(errorCount)) + R"(</span></td>
+				<td><span style="font-weight:600;">)" + htmlTxt(formatNumber(logCount.error + logCount.fatal)) + R"(</span></td>
 			</tr>)";
 
-    if (warningCount > 0)
+    if (logCount.warning > 0)
         output += R"(
 			<tr>
 				<td>)" + htmlTxt(_("Warnings:")) + R"(</td>
 				<td><img src="https://freefilesync.org/images/log/msg-warning.png" width="24" height="24" alt=""></td>
-				<td><span style="font-weight:600;">)" + htmlTxt(formatNumber(warningCount)) + R"(</span></td>
+				<td><span style="font-weight:600;">)" + htmlTxt(formatNumber(logCount.warning)) + R"(</span></td>
 			</tr>)";
 
     output += R"(
@@ -289,7 +293,7 @@ std::string generateLogHeaderHtml(const ProcessSummary& s, const ErrorLog& log,
 )";
 
     //------------ warnings/errors preview ----------------
-    const int logFailTotal = errorCount + warningCount;
+    const int logFailTotal = logCount.warning + logCount.error + logCount.fatal;
     if (logFailTotal > 0)
     {
         output += R"(
@@ -298,13 +302,14 @@ std::string generateLogHeaderHtml(const ProcessSummary& s, const ErrorLog& log,
 	<table class="log-items" style="line-height:1em; border-spacing:0;">
 )";
         int previewCount = 0;
-        for (const LogEntry& entry : log)
-            if (entry.type & (MSG_TYPE_WARNING | MSG_TYPE_ERROR | MSG_TYPE_FATAL_ERROR))
-            {
-                output += formatMessageHtml(entry);
-                if (++previewCount >= logFailsPreviewMax)
-                    break;
-            }
+        if (logFailsPreviewMax > 0)
+            for (const LogEntry& entry : log)
+                if (entry.type & (MSG_TYPE_WARNING | MSG_TYPE_ERROR | MSG_TYPE_FATAL_ERROR))
+                {
+                    output += formatMessageHtml(entry);
+                    if (++previewCount >= logFailsPreviewMax)
+                        break;
+                }
         output += R"(	</table>
 )";
         if (logFailTotal > previewCount)
@@ -337,14 +342,16 @@ std::string generateLogFooterHtml(const std::wstring& logFilePath, int logItemsT
 
     return output += R"(	<br>
 
-	<div>
+	<div style="border-bottom:1px solid #AAA; margin:5px 0;"></div>
+	<div style="font-size:small;">
 		<img src="https://freefilesync.org/images/log/)" + osImage + R"(" width="24" height="24" alt="" style="vertical-align:middle;">
 		<span style="vertical-align:middle;">)" + htmlTxt(getOsDescription()) + /*throw FileError*/ + 
-            " [" + htmlTxt(getUserName()) /*throw FileError*/ + "] &ndash; " + htmlTxt(cm.model) + " &ndash; " + htmlTxt(cm.vendor) + R"(</span>
+            " [" + htmlTxt(getUserName()) /*throw FileError*/ + ']' +
+            (!cm.model .empty() ? " &ndash; " + htmlTxt(cm.model ) : "") +
+            (!cm.vendor.empty() ? " &ndash; " + htmlTxt(cm.vendor) : "") + R"(</span>
 	</div>
-	<div style="border-bottom:1px solid #AAA; margin:5px 0;"></div>
-	<div>
-		<img src="https://freefilesync.org/images/log/log.png" width="24" height="24" alt=")" + htmlTxt(_("Log file")) + R"(:" title=")" + htmlTxt(_("Log file")) + R"(" style="vertical-align:middle;">
+	<div style="font-size:small;">
+		<img src="https://freefilesync.org/images/log/log.png" width="24" height="24" alt=")" + htmlTxt(_("Log file")) + R"(:" style="vertical-align:middle;">
 		<span style="font-family: Consolas,'Courier New',Courier,monospace; vertical-align:middle;">)" + htmlTxt(logFilePath) + R"(</span>
 	</div>
 </body>
@@ -358,59 +365,38 @@ std::string generateLogFooterHtml(const std::wstring& logFilePath, int logItemsT
 void streamToLogFile(const ProcessSummary& summary, //throw FileError
                      const ErrorLog& log,
                      AFS::OutputStream& streamOut,
-                     const AbstractPath& logFilePath)
+                     const AbstractPath& logFilePath,
+                     LogFileFormat logFormat)
 {
-#if 0
-    auto fmtForTxtFile = [needLbReplace = !equalString(LINE_BREAK, '\n')](const std::string& str)
-    {
-        if (needLbReplace)
-            return replaceCpy(str, '\n', LINE_BREAK);
-        return str;
-    };
-
-    std::string buffer = fmtForTxtFile(generateLogHeaderTxt(summary, log, LOG_FAIL_PREVIEW_MAX)); //don't replace line break any earlier
-
-    //write log items in blocks instead of creating one big string: memory allocation might fail; think 1 million entries!
-    for (const LogEntry& entry : log)
-    {
-        buffer += fmtForTxtFile(utfTo<std::string>(formatMessage(entry)));
-
-        streamOut.write(&buffer[0], buffer.size()); //throw FileError, X
-        buffer.clear();
-    }
-
     const int logItemsTotal = log.end() - log.begin();
     const int logItemsPreviewMax = std::numeric_limits<int>::max();
 
-    buffer += fmtForTxtFile(generateLogFooterTxt(AFS::getDisplayPath(logFilePath), logItemsTotal, logItemsPreviewMax)); //throw FileError
-
-    //don't forget to flush:
-    streamOut.write(&buffer[0], buffer.size()); //throw FileError, X
-
-#else
-    std::string buffer = generateLogHeaderHtml(summary, log, LOG_FAIL_PREVIEW_MAX);
+    std::string buffer = logFormat == LogFileFormat::html ? 
+                         generateLogHeaderHtml(summary, log, LOG_FAIL_PREVIEW_MAX) :
+                         generateLogHeaderTxt (summary, log, LOG_FAIL_PREVIEW_MAX);
 
     //write log items in blocks instead of creating one big string: memory allocation might fail; think 1 million entries!
     for (const LogEntry& entry : log)
     {
-        buffer += formatMessageHtml(entry);
+        buffer += logFormat == LogFileFormat::html ?
+                  formatMessageHtml(entry) :
+                  formatMessage    (entry);
 
         streamOut.write(&buffer[0], buffer.size()); //throw FileError, X
         buffer.clear();
     }
 
-    const int logItemsTotal = log.end() - log.begin();
-    const int logItemsPreviewMax = std::numeric_limits<int>::max();
-
-    buffer += generateLogFooterHtml(AFS::getDisplayPath(logFilePath), logItemsTotal, logItemsPreviewMax); //throw FileError
+    buffer += logFormat == LogFileFormat::html ? 
+              generateLogFooterHtml(AFS::getDisplayPath(logFilePath), logItemsTotal, logItemsPreviewMax) : //throw FileError
+              generateLogFooterTxt (AFS::getDisplayPath(logFilePath), logItemsTotal, logItemsPreviewMax);  //throw FileError
 
     //don't forget to flush:
     streamOut.write(&buffer[0], buffer.size()); //throw FileError, X
-#endif
 }
 
 
 void saveNewLogFile(const AbstractPath& logFilePath, //throw FileError, X
+                    LogFileFormat logFormat,
                     const ProcessSummary& summary,
                     const ErrorLog& log,
                     const std::function<void(const std::wstring& msg)>& notifyStatus /*throw X*/)
@@ -437,7 +423,7 @@ void saveNewLogFile(const AbstractPath& logFilePath, //throw FileError, X
     };
 
     std::unique_ptr<AFS::OutputStream> logFileStream = AFS::getOutputStream(logFilePath, std::nullopt /*streamSize*/, std::nullopt /*modTime*/, notifyUnbufferedIO); //throw FileError
-    streamToLogFile(summary, log, *logFileStream, logFilePath); //throw FileError, X
+    streamToLogFile(summary, log, *logFileStream, logFilePath, logFormat); //throw FileError, X
     logFileStream->finalize();                     //throw FileError, X
 }
 
@@ -554,7 +540,7 @@ Zstring fff::getDefaultLogFolderPath() { return getConfigDirPathPf() + Zstr("Log
 
 //"Backup FreeFileSync 2013-09-15 015052.123.html"
 //"Backup FreeFileSync 2013-09-15 015052.123 [Error].html"
-AbstractPath fff::generateLogFilePath(const ProcessSummary& summary, const Zstring& altLogFolderPathPhrase /*optional*/)
+AbstractPath fff::generateLogFilePath(LogFileFormat logFormat, const ProcessSummary& summary, const Zstring& altLogFolderPathPhrase /*optional*/)
 {
     //const std::string colon = "\xcb\xb8"; //="modifier letter raised colon" => regular colon is forbidden in file names on Windows and OS X
     //=> too many issues, most notably cmd.exe is not Unicode-aware: https://freefilesync.org/forum/viewtopic.php?t=1679
@@ -575,7 +561,7 @@ AbstractPath fff::generateLogFilePath(const ProcessSummary& summary, const Zstri
         logFileName.resize(logFileName.size() - 2);
     }
 
-    logFileName += formatTime<Zstring>(Zstr("%Y-%m-%d %H%M%S"), tc) +
+    logFileName += formatTime(Zstr("%Y-%m-%d %H%M%S"), tc) +
                    Zstr(".") + printNumber<Zstring>(Zstr("%03d"), static_cast<int>(timeMs)); //[ms] should yield a fairly unique name
     static_assert(TIME_STAMP_LENGTH == 21);
 
@@ -593,8 +579,11 @@ AbstractPath fff::generateLogFilePath(const ProcessSummary& summary, const Zstri
 
     if (!failStatus.empty())
         logFileName += STATUS_BEGIN_TOKEN + utfTo<Zstring>(failStatus) + STATUS_END_TOKEN;
-    logFileName += Zstr(".html");
 
+    if (logFormat == LogFileFormat::html)
+        logFileName += Zstr(".html");
+    else
+        logFileName += Zstr(".log");
 
     AbstractPath logFolderPath = createAbstractPath(altLogFolderPathPhrase);
     if (AFS::isNullPath(logFolderPath))
@@ -608,13 +597,14 @@ void fff::saveLogFile(const AbstractPath& logFilePath, //throw FileError, X
                       const ProcessSummary& summary,
                       const ErrorLog& log,
                       int logfilesMaxAgeDays,
+                      LogFileFormat logFormat,
                       const std::set<AbstractPath>& logFilePathsToKeep,
                       const std::function<void(const std::wstring& msg)>& notifyStatus /*throw X*/)
 {
     std::exception_ptr firstError;
     try
     {
-        saveNewLogFile(logFilePath, summary, log, notifyStatus); //throw FileError, X
+        saveNewLogFile(logFilePath, logFormat, summary, log, notifyStatus); //throw FileError, X
     }
     catch (const FileError&) { if (!firstError) firstError = std::current_exception(); };
 
@@ -634,7 +624,7 @@ void fff::saveLogFile(const AbstractPath& logFilePath, //throw FileError, X
 
 
 
-void fff::sendLogAsEmail(const Zstring& email, //throw FileError, X
+void fff::sendLogAsEmail(const std::string& email, //throw FileError, X
                          const ProcessSummary& summary,
                          const ErrorLog& log,
                          const AbstractPath& logFilePath,
@@ -644,5 +634,5 @@ void fff::sendLogAsEmail(const Zstring& email, //throw FileError, X
     {
         throw SysError(_("Requires FreeFileSync Donation Edition"));
     }
-    catch (const SysError& e) { throw FileError(replaceCpy(_("Cannot send notification email to %x."), L"%x", utfTo<std::wstring>(email)), e.toString()); }
+    catch (const SysError& e) { throw FileError(replaceCpy(_("Cannot send notification email to %x."), L"%x", L'"' + utfTo<std::wstring>(email) + L'"'), e.toString()); }
 }
diff --git a/FreeFileSync/Source/base/log_file.h b/FreeFileSync/Source/log_file.h
index 3a3a481c..5eec06ad 100644
--- a/FreeFileSync/Source/base/log_file.h
+++ b/FreeFileSync/Source/log_file.h
@@ -11,24 +11,31 @@
 #include <zen/error_log.h>
 #include "return_codes.h"
 #include "status_handler.h"
-#include "../afs/abstract.h"
+#include "afs/abstract.h"
 
 
 namespace fff
 {
 Zstring getDefaultLogFolderPath();
 
+enum class LogFileFormat
+{
+    html,
+    text
+};
+
 
-AbstractPath generateLogFilePath(const ProcessSummary& summary, const Zstring& altLogFolderPathPhrase /*optional*/);
+AbstractPath generateLogFilePath(LogFileFormat logFormat, const ProcessSummary& summary, const Zstring& altLogFolderPathPhrase /*optional*/);
 
 void saveLogFile(const AbstractPath& logFilePath, //throw FileError, X
                  const ProcessSummary& summary,
                  const zen::ErrorLog& log,
                  int logfilesMaxAgeDays,
+                 LogFileFormat logFormat,
                  const std::set<AbstractPath>& logFilePathsToKeep,
                  const std::function<void(const std::wstring& msg)>& notifyStatus /*throw X*/);
 
-void sendLogAsEmail(const Zstring& email, //throw FileError, X
+void sendLogAsEmail(const std::string& email, //throw FileError, X
                     const ProcessSummary& summary,
                     const zen::ErrorLog& log,
                     const AbstractPath& logFilePath,
diff --git a/FreeFileSync/Source/base/parse_lng.h b/FreeFileSync/Source/parse_lng.h
index 361628e4..24f63d3a 100644
--- a/FreeFileSync/Source/base/parse_lng.h
+++ b/FreeFileSync/Source/parse_lng.h
@@ -488,7 +488,7 @@ private:
                 throw ParsingError({ L"The & character to mark a menu item access key must not occur at the end of a string", scn_.posRow(), scn_.posCol() });
 
             //if source ends with colon, so must translation (note: character seems to be universally used, even for asian and arabic languages)
-            if (endsWith(original, ":") && !endsWithColon(translation))
+            if (endsWith(original, ':') && !endsWithColon(translation))
                 throw ParsingError({ L"Source text ends with a colon character \":\", but translation does not", scn_.posRow(), scn_.posCol() });
 
             //if source ends with a period, so must translation (note: character seems to be universally used, even for asian and arabic languages)
@@ -601,7 +601,7 @@ private:
                     throw ParsingError({ L"The & character to mark a menu item access key must not occur at the end of a string", scn_.posRow(), scn_.posCol() });
 
             //if source ends with colon, so must translation (note: character seems to be universally used, even for asian and arabic languages)
-            if (endsWith(original.first, ":") || endsWith(original.second, ":"))
+            if (endsWith(original.first, ':') || endsWith(original.second, ':'))
                 for (const std::string& str : allTexts)
                     if (!endsWithColon(str))
                         throw ParsingError({ L"Source text ends with a colon character \":\", but translation does not", scn_.posRow(), scn_.posCol() });
@@ -659,7 +659,7 @@ private:
     static bool endsWithColon(const std::string& s)
     {
         using namespace zen;
-        return endsWith(s, ":") ||
+        return endsWith(s, ':') ||
                endsWith(s, "\xef\xbc\x9a"); //chinese colon
     }
 
diff --git a/FreeFileSync/Source/base/parse_plural.h b/FreeFileSync/Source/parse_plural.h
index 242dd4a6..242dd4a6 100644
--- a/FreeFileSync/Source/base/parse_plural.h
+++ b/FreeFileSync/Source/parse_plural.h
diff --git a/FreeFileSync/Source/base/perf_check.cpp b/FreeFileSync/Source/perf_check.cpp
index 9493a8a2..9493a8a2 100644
--- a/FreeFileSync/Source/base/perf_check.cpp
+++ b/FreeFileSync/Source/perf_check.cpp
diff --git a/FreeFileSync/Source/base/perf_check.h b/FreeFileSync/Source/perf_check.h
index 2e9ccc6d..2e9ccc6d 100644
--- a/FreeFileSync/Source/base/perf_check.h
+++ b/FreeFileSync/Source/perf_check.h
diff --git a/FreeFileSync/Source/base/return_codes.h b/FreeFileSync/Source/return_codes.h
index 0fe72022..ad9318c6 100644
--- a/FreeFileSync/Source/base/return_codes.h
+++ b/FreeFileSync/Source/return_codes.h
@@ -59,7 +59,7 @@ FfsReturnCode mapToReturnCode(SyncResult syncStatus)
 
 
 inline
-std::wstring getResultsStatusLabel(SyncResult resultStatus)
+std::wstring getSyncResultLabel(SyncResult resultStatus)
 {
     switch (resultStatus)
     {
diff --git a/FreeFileSync/Source/base/status_handler.cpp b/FreeFileSync/Source/status_handler.cpp
index 19d1e882..19d1e882 100644
--- a/FreeFileSync/Source/base/status_handler.cpp
+++ b/FreeFileSync/Source/status_handler.cpp
diff --git a/FreeFileSync/Source/base/status_handler.h b/FreeFileSync/Source/status_handler.h
index 339f9ebe..9058033b 100644
--- a/FreeFileSync/Source/base/status_handler.h
+++ b/FreeFileSync/Source/status_handler.h
@@ -13,7 +13,7 @@
 #include <string>
 #include <zen/i18n.h>
 #include <zen/basic_math.h>
-#include "process_callback.h"
+#include "base/process_callback.h"
 #include "return_codes.h"
 
 
diff --git a/FreeFileSync/Source/ui/abstract_folder_picker.cpp b/FreeFileSync/Source/ui/abstract_folder_picker.cpp
index 4c96e6f7..8f2fe782 100644
--- a/FreeFileSync/Source/ui/abstract_folder_picker.cpp
+++ b/FreeFileSync/Source/ui/abstract_folder_picker.cpp
@@ -11,7 +11,7 @@
 #include <wx+/popup_dlg.h>
 #include <wx+/image_tools.h>
 #include "gui_generated.h"
-#include "../base/icon_buffer.h"
+#include "../icon_buffer.h"
 
 using namespace zen;
 using namespace fff;
@@ -264,7 +264,7 @@ void AbstractFolderPickerDlg::findAndNavigateToExistingPath(const AbstractPath&
     if (!AFS::getParentPath(folderPath))
         return m_staticTextStatus->SetLabel(L"");
 
-    m_staticTextStatus->SetLabel(_("Scanning...") + L" " + utfTo<std::wstring>(FILE_NAME_SEPARATOR + folderPath.afsPath.value)); //keep it short!
+    m_staticTextStatus->SetLabel(_("Scanning...") + L' ' + utfTo<std::wstring>(FILE_NAME_SEPARATOR + folderPath.afsPath.value)); //keep it short!
 
     guiQueue_.processAsync([folderPath]() -> std::optional<AFS::ItemType>
     {
diff --git a/FreeFileSync/Source/ui/batch_config.cpp b/FreeFileSync/Source/ui/batch_config.cpp
index b158a8ca..51e6eda3 100644
--- a/FreeFileSync/Source/ui/batch_config.cpp
+++ b/FreeFileSync/Source/ui/batch_config.cpp
@@ -14,7 +14,7 @@
 #include <wx+/popup_dlg.h>
 #include "gui_generated.h"
 #include "folder_selector.h"
-#include "../base/help_provider.h"
+#include "../help_provider.h"
 
 
 using namespace zen;
diff --git a/FreeFileSync/Source/ui/batch_config.h b/FreeFileSync/Source/ui/batch_config.h
index 7bb406b3..35fb73fa 100644
--- a/FreeFileSync/Source/ui/batch_config.h
+++ b/FreeFileSync/Source/ui/batch_config.h
@@ -8,7 +8,7 @@
 #define BATCH_CONFIG_H_3921674832168945
 
 #include <wx/window.h>
-#include "../base/config.h"
+#include "../config.h"
 
 
 namespace fff
diff --git a/FreeFileSync/Source/ui/batch_status_handler.cpp b/FreeFileSync/Source/ui/batch_status_handler.cpp
index 28f1833c..40098bca 100644
--- a/FreeFileSync/Source/ui/batch_status_handler.cpp
+++ b/FreeFileSync/Source/ui/batch_status_handler.cpp
@@ -9,9 +9,9 @@
 #include <zen/shutdown.h>
 #include <wx+/popup_dlg.h>
 #include <wx/app.h>
-#include "../base/resolve_path.h"
-#include "../base/log_file.h"
 #include "../afs/concrete.h"
+#include "../base/resolve_path.h"
+#include "../log_file.h"
 
 using namespace zen;
 using namespace fff;
@@ -61,8 +61,9 @@ BatchStatusHandler::~BatchStatusHandler()
 
 
 BatchStatusHandler::Result BatchStatusHandler::reportResults(const Zstring& postSyncCommand, PostSyncCondition postSyncCondition,
-                                                             const Zstring& altLogFolderPathPhrase, int logfilesMaxAgeDays, const std::set<AbstractPath>& logFilePathsToKeep,
-                                                             const Zstring& emailNotifyAddress, ResultsNotification emailNotifyCondition) //noexcept!!
+                                                             const Zstring& altLogFolderPathPhrase, int logfilesMaxAgeDays, LogFileFormat logFormat,
+                                                             const std::set<AbstractPath>& logFilePathsToKeep,
+                                                             const std::string& emailNotifyAddress, ResultsNotification emailNotifyCondition) //noexcept!!
 {
     const auto totalTime = std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock::now() - startTime_);
 
@@ -76,9 +77,10 @@ BatchStatusHandler::Result BatchStatusHandler::reportResults(const Zstring& post
             errorLog_.logMsg(_("Stopped"), MSG_TYPE_ERROR); //= user cancel; *not* a MSG_TYPE_FATAL_ERROR!
             return SyncResult::aborted;
         }
-        else if (errorLog_.getItemCount(MSG_TYPE_ERROR | MSG_TYPE_FATAL_ERROR) > 0)
+        const ErrorLog::Stats logCount = errorLog_.getStats();
+        if (logCount.error + logCount.fatal > 0)
             return SyncResult::finishedError;
-        else if (errorLog_.getItemCount(MSG_TYPE_WARNING) > 0)
+        else if (logCount.warning > 0)
             return SyncResult::finishedWarning;
 
         if (getStatsTotal() == ProgressStats())
@@ -96,7 +98,7 @@ BatchStatusHandler::Result BatchStatusHandler::reportResults(const Zstring& post
         totalTime
     };
 
-    const AbstractPath logFilePath = generateLogFilePath(summary, altLogFolderPathPhrase);
+    const AbstractPath logFilePath = generateLogFilePath(logFormat, summary, altLogFolderPathPhrase);
     //e.g. %AppData%\FreeFileSync\Logs\Backup FreeFileSync 2013-09-15 015052.123 [Error].log
 
     if (const Zstring cmdLine = trimCpy(postSyncCommand);
@@ -113,9 +115,8 @@ BatchStatusHandler::Result BatchStatusHandler::reportResults(const Zstring& post
                 //::wxSetEnv(L"logfile_path", AFS::getDisplayPath(logFilePath));
                 ////----------------------------------------------------------------------
                 const Zstring cmdLineExp = expandMacros(cmdLine);
-                const int exitCode = shellExecute(cmdLineExp, ExecutionType::sync, false /*hideConsole*/); //throw FileError
-                errorLog_.logMsg(_("Executing command:") + L" " + utfTo<std::wstring>(cmdLineExp) + L" [" + replaceCpy(_("Exit Code %x"), L"%x", numberTo<std::wstring>(exitCode)) + L']',
-                                 exitCode == 0 ? MSG_TYPE_INFO : MSG_TYPE_ERROR);
+                errorLog_.logMsg(_("Executing command:") + L' ' + utfTo<std::wstring>(cmdLineExp), MSG_TYPE_INFO);
+                shellExecute(cmdLineExp, ExecutionType::async, false /*hideConsole*/); //throw FileError
             }
             catch (const FileError& e) { errorLog_.logMsg(e.toString(), MSG_TYPE_ERROR); }
     }
@@ -123,7 +124,7 @@ BatchStatusHandler::Result BatchStatusHandler::reportResults(const Zstring& post
     //---------------------------- save log file ------------------------------
     auto notifyStatusNoThrow = [&](const std::wstring& msg) { try { updateStatus(msg); /*throw AbortProcess*/ } catch (AbortProcess&) {} };
 
-    if (const Zstring notifyEmail = trimCpy(emailNotifyAddress);
+    if (const std::string notifyEmail = trimCpy(emailNotifyAddress);
         !notifyEmail.empty())
     {
         if (getAbortStatus() && *getAbortStatus() == AbortTrigger::user)
@@ -144,7 +145,7 @@ BatchStatusHandler::Result BatchStatusHandler::reportResults(const Zstring& post
     try //create not before destruction: 1. avoid issues with FFS trying to sync open log file 2. include status in log file name without extra rename
     {
         //do NOT use tryReportingError()! saving log files should not be cancellable!
-        saveLogFile(logFilePath, summary, errorLog_, logfilesMaxAgeDays, logFilePathsToKeep, notifyStatusNoThrow); //throw FileError
+        saveLogFile(logFilePath, summary, errorLog_, logfilesMaxAgeDays, logFormat, logFilePathsToKeep, notifyStatusNoThrow); //throw FileError
     }
     catch (const FileError& e) { errorLog_.logMsg(e.toString(), MSG_TYPE_ERROR); }
 
@@ -299,7 +300,7 @@ ProcessCallback::Response BatchStatusHandler::reportError(const std::wstring& ms
     if (retryNumber < automaticRetryCount_)
     {
         errorLog_.logMsg(msg + L"\n-> " + _("Automatic retry"), MSG_TYPE_INFO);
-        delayAndCountDown(_("Automatic retry") + (automaticRetryCount_ <= 1 ? L"" :  L" " + numberTo<std::wstring>(retryNumber + 1) + L"/" + numberTo<std::wstring>(automaticRetryCount_)),
+        delayAndCountDown(_("Automatic retry") + (automaticRetryCount_ <= 1 ? L"" :  L' ' + numberTo<std::wstring>(retryNumber + 1) + L"/" + numberTo<std::wstring>(automaticRetryCount_)),
         automaticRetryDelay_, [&](const std::wstring& statusMsg) { this->updateStatus(_("Error") + L": " + statusMsg); }); //throw AbortProcess
         return ProcessCallback::retry;
     }
diff --git a/FreeFileSync/Source/ui/batch_status_handler.h b/FreeFileSync/Source/ui/batch_status_handler.h
index b56a4aed..2e59ac7e 100644
--- a/FreeFileSync/Source/ui/batch_status_handler.h
+++ b/FreeFileSync/Source/ui/batch_status_handler.h
@@ -10,8 +10,8 @@
 #include <chrono>
 #include <zen/error_log.h>
 #include "progress_indicator.h"
-#include "../base/config.h"
-#include "../base/status_handler.h"
+#include "../config.h"
+#include "../status_handler.h"
 
 
 namespace fff
@@ -54,8 +54,8 @@ public:
         AbstractPath logFilePath;
     };
     Result reportResults(const Zstring& postSyncCommand, PostSyncCondition postSyncCondition,
-                         const Zstring& altLogFolderPathPhrase, int logfilesMaxAgeDays, const std::set<AbstractPath>& logFilePathsToKeep,
-                         const Zstring& emailNotifyAddress, ResultsNotification emailNotifyCondition); //noexcept!!
+                         const Zstring& altLogFolderPathPhrase, int logfilesMaxAgeDays, LogFileFormat logFormat, const std::set<AbstractPath>& logFilePathsToKeep,
+                         const std::string& emailNotifyAddress, ResultsNotification emailNotifyCondition); //noexcept!!
 
 private:
     bool switchToGuiRequested_ = false;
diff --git a/FreeFileSync/Source/ui/cfg_grid.cpp b/FreeFileSync/Source/ui/cfg_grid.cpp
index 7ae27b42..fca67704 100644
--- a/FreeFileSync/Source/ui/cfg_grid.cpp
+++ b/FreeFileSync/Source/ui/cfg_grid.cpp
@@ -13,8 +13,8 @@
 #include <wx+/image_resources.h>
 #include <wx+/popup_dlg.h>
 #include <wx/settings.h>
-#include "../base/icon_buffer.h"
-#include "../base/ffs_paths.h"
+#include "../icon_buffer.h"
+#include "../ffs_paths.h"
 
 using namespace zen;
 using namespace fff;
@@ -88,13 +88,13 @@ void ConfigView::addCfgFilesImpl(const std::vector<Zstring>& filePaths)
             std::tie(detail.name, detail.cfgType, detail.isLastRunCfg) = [&]
             {
                 if (equalNativePath(filePath, lastRunConfigPath_))
-                    return std::make_tuple(utfTo<Zstring>(L"[" + _("Last session") + L"]"), Details::CFG_TYPE_GUI, true);
+                    return std::make_tuple(utfTo<Zstring>(L'[' + _("Last session") + L']'), Details::CFG_TYPE_GUI, true);
 
                 const Zstring fileName = afterLast(filePath, FILE_NAME_SEPARATOR, IF_MISSING_RETURN_ALL);
 
-                if (endsWithAsciiNoCase(fileName, Zstr(".ffs_gui")))
+                if (endsWithAsciiNoCase(fileName, ".ffs_gui"))
                     return std::make_tuple(beforeLast(fileName, Zstr('.'), IF_MISSING_RETURN_NONE), Details::CFG_TYPE_GUI, false);
-                else if (endsWithAsciiNoCase(fileName, Zstr(".ffs_batch")))
+                else if (endsWithAsciiNoCase(fileName, ".ffs_batch"))
                     return std::make_tuple(beforeLast(fileName, Zstr('.'), IF_MISSING_RETURN_NONE), Details::CFG_TYPE_BATCH, false);
                 else
                     return std::make_tuple(fileName, Details::CFG_TYPE_NONE, false);
@@ -320,14 +320,14 @@ private:
 
                         const int daysPast = getDaysPast(item->cfgItem.lastSyncTime);
                         return daysPast == 0 ? _("Today") : _P("1 day", "%x days", daysPast);
-                        //return formatTime<std::wstring>(FORMAT_DATE_TIME, getLocalTime(item->lastSyncTime));
+                        //return formatTime(formatDateTimeTag, getLocalTime(item->lastSyncTime));
                     }
                     break;
 
                 case ColumnTypeCfg::lastLog:
                     if (!item->isLastRunCfg &&
                         !AFS::isNullPath(item->cfgItem.logFilePath))
-                        return getResultsStatusLabel(item->cfgItem.logResult);
+                        return getSyncResultLabel(item->cfgItem.logResult);
                     break;
             }
         return std::wstring();
@@ -570,7 +570,7 @@ private:
 
                     if (!item->isLastRunCfg &&
                         !AFS::isNullPath(item->cfgItem.logFilePath))
-                        return getResultsStatusLabel(item->cfgItem.logResult) + SPACED_DASH + AFS::getDisplayPath(item->cfgItem.logFilePath);
+                        return getSyncResultLabel(item->cfgItem.logResult) + SPACED_DASH + AFS::getDisplayPath(item->cfgItem.logFilePath);
                     break;
             }
         return std::wstring();
@@ -630,7 +630,7 @@ ConfigView& cfggrid::getDataView(Grid& grid)
 {
     if (auto* prov = dynamic_cast<GridDataCfg*>(grid.getDataProvider()))
         return prov->getDataView();
-    throw std::runtime_error(std::string(__FILE__) + "[" + numberTo<std::string>(__LINE__) + "] cfggrid was not initialized.");
+    throw std::runtime_error(std::string(__FILE__) + '[' + numberTo<std::string>(__LINE__) + "] cfggrid was not initialized.");
 }
 
 
@@ -662,7 +662,7 @@ int cfggrid::getSyncOverdueDays(Grid& grid)
 {
     if (auto* prov = dynamic_cast<GridDataCfg*>(grid.getDataProvider()))
         return prov->getSyncOverdueDays();
-    throw std::runtime_error(std::string(__FILE__) + "[" + numberTo<std::string>(__LINE__) + "] cfggrid was not initialized.");
+    throw std::runtime_error(std::string(__FILE__) + '[' + numberTo<std::string>(__LINE__) + "] cfggrid was not initialized.");
 }
 
 
@@ -670,7 +670,7 @@ void cfggrid::setSyncOverdueDays(Grid& grid, int syncOverdueDays)
 {
     auto* prov = dynamic_cast<GridDataCfg*>(grid.getDataProvider());
     if (!prov)
-        throw std::runtime_error(std::string(__FILE__) + "[" + numberTo<std::string>(__LINE__) + "] cfggrid was not initialized.");
+        throw std::runtime_error(std::string(__FILE__) + '[' + numberTo<std::string>(__LINE__) + "] cfggrid was not initialized.");
 
     prov->setSyncOverdueDays(syncOverdueDays);
     grid.Refresh();
diff --git a/FreeFileSync/Source/ui/cfg_grid.h b/FreeFileSync/Source/ui/cfg_grid.h
index 3ace5ff7..5be3ce71 100644
--- a/FreeFileSync/Source/ui/cfg_grid.h
+++ b/FreeFileSync/Source/ui/cfg_grid.h
@@ -10,7 +10,7 @@
 #include <wx+/grid.h>
 #include <wx+/dc.h>
 #include <zen/zstring.h>
-#include "../base/return_codes.h"
+#include "../return_codes.h"
 #include "../afs/concrete.h"
 
 
diff --git a/FreeFileSync/Source/ui/file_grid.cpp b/FreeFileSync/Source/ui/file_grid.cpp
index 12ff49f8..93708754 100644
--- a/FreeFileSync/Source/ui/file_grid.cpp
+++ b/FreeFileSync/Source/ui/file_grid.cpp
@@ -739,15 +739,15 @@ private:
                 visitFSObject(*fsObj, [](const FolderPair& folder) {},
                 [&](const FilePair& file)
                 {
-                    toolTip += L"\n" +
-                               _("Size:") + L" " + zen::formatFilesizeShort(file.getFileSize<side>()) + L"\n" +
-                               _("Date:") + L" " + zen::formatUtcToLocalTime(file.getLastWriteTime<side>());
+                    toolTip += L'\n' +
+                               _("Size:") + L' ' + zen::formatFilesizeShort(file.getFileSize<side>()) + L'\n' +
+                               _("Date:") + L' ' + zen::formatUtcToLocalTime(file.getLastWriteTime<side>());
                 },
 
                 [&](const SymlinkPair& symlink)
                 {
-                    toolTip += L"\n" +
-                               _("Date:") + L" " + zen::formatUtcToLocalTime(symlink.getLastWriteTime<side>());
+                    toolTip += L'\n' +
+                               _("Date:") + L' ' + zen::formatUtcToLocalTime(symlink.getLastWriteTime<side>());
                 });
             }
         return toolTip;
@@ -1607,7 +1607,7 @@ FileView& filegrid::getDataView(Grid& grid)
     if (auto* prov = dynamic_cast<GridDataBase*>(grid.getDataProvider()))
         return prov->getDataView();
 
-    throw std::runtime_error("filegrid was not initialized! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+    throw std::runtime_error("filegrid was not initialized! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
 }
 
 
diff --git a/FreeFileSync/Source/ui/file_grid.h b/FreeFileSync/Source/ui/file_grid.h
index a416a0d0..2fadb7c8 100644
--- a/FreeFileSync/Source/ui/file_grid.h
+++ b/FreeFileSync/Source/ui/file_grid.h
@@ -10,7 +10,7 @@
 #include <wx+/grid.h>
 #include "file_view.h"
 #include "file_grid_attr.h"
-#include "../base/icon_buffer.h"
+#include "../icon_buffer.h"
 
 
 namespace fff
diff --git a/FreeFileSync/Source/ui/folder_pair.h b/FreeFileSync/Source/ui/folder_pair.h
index 419fc751..c3ee65bb 100644
--- a/FreeFileSync/Source/ui/folder_pair.h
+++ b/FreeFileSync/Source/ui/folder_pair.h
@@ -17,7 +17,7 @@
 #include "small_dlgs.h"
 #include "sync_cfg.h"
 #include "../base/norm_filter.h"
-#include "../base/structures.h"
+#include "../base_tools.h"
 
 
 namespace fff
diff --git a/FreeFileSync/Source/ui/folder_selector.cpp b/FreeFileSync/Source/ui/folder_selector.cpp
index 9afdfe3c..8e2037ba 100644
--- a/FreeFileSync/Source/ui/folder_selector.cpp
+++ b/FreeFileSync/Source/ui/folder_selector.cpp
@@ -15,7 +15,7 @@
 #include "small_dlgs.h" //includes structures.h, which defines "AFS"
 #include "../afs/concrete.h"
 #include "../afs/native.h"
-#include "../base/icon_buffer.h"
+#include "../icon_buffer.h"
 
 
 
@@ -49,6 +49,7 @@ void setFolderPathPhrase(const Zstring& folderPathPhrase, FolderHistoryBox* comb
     }
 }
 
+
 }
 
 //##############################################################################################################
diff --git a/FreeFileSync/Source/ui/gui_generated.cpp b/FreeFileSync/Source/ui/gui_generated.cpp
index 80dd34d5..78092e06 100644
--- a/FreeFileSync/Source/ui/gui_generated.cpp
+++ b/FreeFileSync/Source/ui/gui_generated.cpp
@@ -619,14 +619,14 @@ MainDialogGenerated::MainDialogGenerated( wxWindow* parent, wxWindowID id, const
 
     bSizer42 = new wxBoxSizer( wxHORIZONTAL );
 
-    m_bitmapLogStatus = new wxStaticBitmap( m_panelLog, wxID_ANY, wxNullBitmap, wxDefaultPosition, wxSize( -1, -1 ), 0 );
-    bSizer42->Add( m_bitmapLogStatus, 0, wxALIGN_CENTER_VERTICAL|wxALL, 5 );
+    m_bitmapSyncResult = new wxStaticBitmap( m_panelLog, wxID_ANY, wxNullBitmap, wxDefaultPosition, wxSize( -1, -1 ), 0 );
+    bSizer42->Add( m_bitmapSyncResult, 0, wxALIGN_CENTER_VERTICAL|wxALL, 5 );
 
-    m_staticTextLogStatus = new wxStaticText( m_panelLog, wxID_ANY, _("dummy"), wxDefaultPosition, wxDefaultSize, 0 );
-    m_staticTextLogStatus->Wrap( -1 );
-    m_staticTextLogStatus->SetFont( wxFont( wxNORMAL_FONT->GetPointSize(), wxFONTFAMILY_DEFAULT, wxFONTSTYLE_NORMAL, wxFONTWEIGHT_BOLD, false, wxEmptyString ) );
+    m_staticTextSyncResult = new wxStaticText( m_panelLog, wxID_ANY, _("dummy"), wxDefaultPosition, wxDefaultSize, 0 );
+    m_staticTextSyncResult->Wrap( -1 );
+    m_staticTextSyncResult->SetFont( wxFont( wxNORMAL_FONT->GetPointSize(), wxFONTFAMILY_DEFAULT, wxFONTSTYLE_NORMAL, wxFONTWEIGHT_BOLD, false, wxEmptyString ) );
 
-    bSizer42->Add( m_staticTextLogStatus, 0, wxALIGN_CENTER_HORIZONTAL|wxALIGN_CENTER_VERTICAL|wxTOP|wxBOTTOM|wxRIGHT, 10 );
+    bSizer42->Add( m_staticTextSyncResult, 0, wxALIGN_CENTER_HORIZONTAL|wxALIGN_CENTER_VERTICAL|wxTOP|wxBOTTOM|wxRIGHT, 10 );
 
 
     bSizer42->Add( 10, 0, 0, 0, 5 );
@@ -1421,7 +1421,7 @@ ConfigDlgGenerated::ConfigDlgGenerated( wxWindow* parent, wxWindowID id, const w
     bSizer176->Add( m_radioBtnSymlinksDirect, 0, wxEXPAND|wxBOTTOM|wxRIGHT|wxLEFT, 5 );
 
 
-    bSizer1721->Add( bSizer176, 0, wxLEFT|wxEXPAND, 18 );
+    bSizer1721->Add( bSizer176, 0, wxLEFT|wxEXPAND, 15 );
 
 
     bSizer1721->Add( 0, 0, 1, wxEXPAND, 5 );
@@ -2270,10 +2270,10 @@ ConfigDlgGenerated::ConfigDlgGenerated( wxWindow* parent, wxWindowID id, const w
     bSizer291 = new wxBoxSizer( wxHORIZONTAL );
 
     m_bitmapEmail = new wxStaticBitmap( m_panelSyncSettings, wxID_ANY, wxNullBitmap, wxDefaultPosition, wxDefaultSize, 0 );
-    bSizer291->Add( m_bitmapEmail, 0, wxRIGHT|wxALIGN_CENTER_VERTICAL, 5 );
+    bSizer291->Add( m_bitmapEmail, 0, wxALIGN_CENTER_VERTICAL, 5 );
 
     m_checkBoxSendEmail = new wxCheckBox( m_panelSyncSettings, wxID_ANY, _("Send email notification:"), wxDefaultPosition, wxDefaultSize, 0 );
-    bSizer291->Add( m_checkBoxSendEmail, 0, wxALIGN_CENTER_VERTICAL, 5 );
+    bSizer291->Add( m_checkBoxSendEmail, 0, wxALIGN_CENTER_VERTICAL|wxLEFT, 5 );
 
 
     bSizer290->Add( bSizer291, 0, 0, 5 );
@@ -2282,22 +2282,22 @@ ConfigDlgGenerated::ConfigDlgGenerated( wxWindow* parent, wxWindowID id, const w
     bSizer290->Add( m_comboBoxEmail, 0, wxEXPAND|wxTOP, 5 );
 
 
-    bSizer287->Add( bSizer290, 1, 0, 5 );
+    bSizer287->Add( bSizer290, 1, wxRIGHT, 5 );
 
     wxBoxSizer* bSizer289;
     bSizer289 = new wxBoxSizer( wxVERTICAL );
 
     m_bpButtonEmailAlways = new wxBitmapButton( m_panelSyncSettings, wxID_ANY, wxNullBitmap, wxDefaultPosition, wxDefaultSize, wxBU_AUTODRAW|0 );
-    bSizer289->Add( m_bpButtonEmailAlways, 0, wxLEFT, 5 );
+    bSizer289->Add( m_bpButtonEmailAlways, 0, 0, 5 );
 
     m_bpButtonEmailErrorWarning = new wxBitmapButton( m_panelSyncSettings, wxID_ANY, wxNullBitmap, wxDefaultPosition, wxDefaultSize, wxBU_AUTODRAW|0 );
-    bSizer289->Add( m_bpButtonEmailErrorWarning, 0, wxLEFT, 5 );
+    bSizer289->Add( m_bpButtonEmailErrorWarning, 0, 0, 5 );
 
     m_bpButtonEmailErrorOnly = new wxBitmapButton( m_panelSyncSettings, wxID_ANY, wxNullBitmap, wxDefaultPosition, wxDefaultSize, wxBU_AUTODRAW|0 );
-    bSizer289->Add( m_bpButtonEmailErrorOnly, 0, wxLEFT, 5 );
+    bSizer289->Add( m_bpButtonEmailErrorOnly, 0, 0, 5 );
 
 
-    bSizer287->Add( bSizer289, 0, 0, 5 );
+    bSizer287->Add( bSizer289, 0, wxLEFT, 5 );
 
 
     bSizer292->Add( bSizer287, 0, wxEXPAND, 5 );
@@ -2328,11 +2328,11 @@ ConfigDlgGenerated::ConfigDlgGenerated( wxWindow* parent, wxWindowID id, const w
     bSizer279 = new wxBoxSizer( wxHORIZONTAL );
 
     m_bitmapLogFile = new wxStaticBitmap( m_panelLogfile, wxID_ANY, wxNullBitmap, wxDefaultPosition, wxDefaultSize, 0 );
-    bSizer279->Add( m_bitmapLogFile, 0, wxALIGN_CENTER_VERTICAL|wxRIGHT, 5 );
+    bSizer279->Add( m_bitmapLogFile, 0, wxALIGN_CENTER_VERTICAL, 5 );
 
     m_checkBoxOverrideLogPath = new wxCheckBox( m_panelLogfile, wxID_ANY, _("&Override default log path:"), wxDefaultPosition, wxDefaultSize, 0 );
     m_checkBoxOverrideLogPath->SetValue(true);
-    bSizer279->Add( m_checkBoxOverrideLogPath, 1, wxALIGN_CENTER_VERTICAL|wxALL, 5 );
+    bSizer279->Add( m_checkBoxOverrideLogPath, 1, wxALIGN_CENTER_VERTICAL|wxRIGHT|wxLEFT, 5 );
 
     m_buttonSelectLogFolder = new wxButton( m_panelLogfile, wxID_ANY, _("Browse"), wxDefaultPosition, wxDefaultSize, 0 );
     m_buttonSelectLogFolder->SetToolTip( _("Select a folder") );
@@ -2443,7 +2443,7 @@ ConfigDlgGenerated::ConfigDlgGenerated( wxWindow* parent, wxWindowID id, const w
     m_checkBoxAutoRetry->Connect( wxEVT_COMMAND_CHECKBOX_CLICKED, wxCommandEventHandler( ConfigDlgGenerated::OnToggleAutoRetry ), NULL, this );
     m_hyperlink1711->Connect( wxEVT_COMMAND_HYPERLINK, wxHyperlinkEventHandler( ConfigDlgGenerated::OnHelpPerformance ), NULL, this );
     m_textCtrlInclude->Connect( wxEVT_COMMAND_TEXT_UPDATED, wxCommandEventHandler( ConfigDlgGenerated::OnChangeFilterOption ), NULL, this );
-    m_hyperlink171->Connect( wxEVT_COMMAND_HYPERLINK, wxHyperlinkEventHandler( ConfigDlgGenerated::OnHelpShowExamples ), NULL, this );
+    m_hyperlink171->Connect( wxEVT_COMMAND_HYPERLINK, wxHyperlinkEventHandler( ConfigDlgGenerated::OnHelpFilterSettings ), NULL, this );
     m_textCtrlExclude->Connect( wxEVT_COMMAND_TEXT_UPDATED, wxCommandEventHandler( ConfigDlgGenerated::OnChangeFilterOption ), NULL, this );
     m_choiceUnitMinSize->Connect( wxEVT_COMMAND_CHOICE_SELECTED, wxCommandEventHandler( ConfigDlgGenerated::OnChangeFilterOption ), NULL, this );
     m_choiceUnitMaxSize->Connect( wxEVT_COMMAND_CHOICE_SELECTED, wxCommandEventHandler( ConfigDlgGenerated::OnChangeFilterOption ), NULL, this );
@@ -2474,7 +2474,7 @@ ConfigDlgGenerated::ConfigDlgGenerated( wxWindow* parent, wxWindowID id, const w
     m_checkBoxVersionMaxDays->Connect( wxEVT_COMMAND_CHECKBOX_CLICKED, wxCommandEventHandler( ConfigDlgGenerated::OnToggleVersioningLimit ), NULL, this );
     m_checkBoxVersionCountMin->Connect( wxEVT_COMMAND_CHECKBOX_CLICKED, wxCommandEventHandler( ConfigDlgGenerated::OnToggleVersioningLimit ), NULL, this );
     m_checkBoxVersionCountMax->Connect( wxEVT_COMMAND_CHECKBOX_CLICKED, wxCommandEventHandler( ConfigDlgGenerated::OnToggleVersioningLimit ), NULL, this );
-    m_checkBoxSendEmail->Connect( wxEVT_COMMAND_CHECKBOX_CLICKED, wxCommandEventHandler( ConfigDlgGenerated::OnToggleMiscOption ), NULL, this );
+    m_checkBoxSendEmail->Connect( wxEVT_COMMAND_CHECKBOX_CLICKED, wxCommandEventHandler( ConfigDlgGenerated::OnToggleMiscEmail ), NULL, this );
     m_bpButtonEmailAlways->Connect( wxEVT_COMMAND_BUTTON_CLICKED, wxCommandEventHandler( ConfigDlgGenerated::OnEmailAlways ), NULL, this );
     m_bpButtonEmailErrorWarning->Connect( wxEVT_COMMAND_BUTTON_CLICKED, wxCommandEventHandler( ConfigDlgGenerated::OnEmailErrorWarning ), NULL, this );
     m_bpButtonEmailErrorOnly->Connect( wxEVT_COMMAND_BUTTON_CLICKED, wxCommandEventHandler( ConfigDlgGenerated::OnEmailErrorOnly ), NULL, this );
@@ -3937,7 +3937,7 @@ BatchDlgGenerated::BatchDlgGenerated( wxWindow* parent, wxWindowID id, const wxS
     bSizer243->Add( m_checkBoxIgnoreErrors, 1, wxALIGN_CENTER_VERTICAL|wxLEFT, 5 );
 
 
-    bSizer242->Add( bSizer243, 0, wxTOP|wxRIGHT|wxLEFT|wxALIGN_CENTER_HORIZONTAL, 5 );
+    bSizer242->Add( bSizer243, 0, wxTOP|wxRIGHT|wxLEFT, 5 );
 
     wxBoxSizer* bSizer246;
     bSizer246 = new wxBoxSizer( wxVERTICAL );
@@ -3954,7 +3954,7 @@ BatchDlgGenerated::BatchDlgGenerated( wxWindow* parent, wxWindowID id, const wxS
     bSizer246->Add( m_radioBtnErrorDialogCancel, 0, wxBOTTOM|wxRIGHT|wxLEFT|wxEXPAND, 5 );
 
 
-    bSizer242->Add( bSizer246, 0, wxALIGN_CENTER_HORIZONTAL, 5 );
+    bSizer242->Add( bSizer246, 0, wxALIGN_CENTER_HORIZONTAL|wxLEFT, 15 );
 
 
     bSizer180->Add( bSizer242, 0, wxALL|wxALIGN_CENTER_VERTICAL, 5 );
@@ -4372,11 +4372,17 @@ OptionsDlgGenerated::OptionsDlgGenerated( wxWindow* parent, wxWindowID id, const
     bSizer160->Add( bSizer178, 0, wxEXPAND, 5 );
 
 
-    bSizer186->Add( bSizer160, 0, wxALL|wxALIGN_CENTER_VERTICAL, 5 );
+    bSizer186->Add( bSizer160, 0, wxALIGN_CENTER_VERTICAL|wxALL, 5 );
 
     m_staticline39 = new wxStaticLine( m_panel39, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxLI_VERTICAL );
     bSizer186->Add( m_staticline39, 0, wxEXPAND, 5 );
 
+    wxBoxSizer* bSizer293;
+    bSizer293 = new wxBoxSizer( wxHORIZONTAL );
+
+    m_bitmapWarnings = new wxStaticBitmap( m_panel39, wxID_ANY, wxNullBitmap, wxDefaultPosition, wxDefaultSize, 0 );
+    bSizer293->Add( m_bitmapWarnings, 0, wxALL, 5 );
+
     wxBoxSizer* bSizer1881;
     bSizer1881 = new wxBoxSizer( wxVERTICAL );
 
@@ -4384,13 +4390,26 @@ OptionsDlgGenerated::OptionsDlgGenerated( wxWindow* parent, wxWindowID id, const
     m_staticTextResetDialogs->Wrap( -1 );
     m_staticTextResetDialogs->SetForegroundColour( wxSystemSettings::GetColour( wxSYS_COLOUR_GRAYTEXT ) );
 
-    bSizer1881->Add( m_staticTextResetDialogs, 0, wxTOP|wxRIGHT|wxLEFT, 5 );
+    bSizer1881->Add( m_staticTextResetDialogs, 0, 0, 5 );
+
+    wxBoxSizer* bSizer292;
+    bSizer292 = new wxBoxSizer( wxHORIZONTAL );
+
+    m_buttonRestoreDialogs = new wxButton( m_panel39, wxID_ANY, _("&Restore"), wxDefaultPosition, wxSize( -1, -1 ), 0 );
+    bSizer292->Add( m_buttonRestoreDialogs, 0, wxALIGN_CENTER_VERTICAL, 5 );
+
+    m_staticTextAllDialogsShown = new wxStaticText( m_panel39, wxID_ANY, _("dummy"), wxDefaultPosition, wxDefaultSize, 0 );
+    m_staticTextAllDialogsShown->Wrap( -1 );
+    bSizer292->Add( m_staticTextAllDialogsShown, 0, wxALIGN_CENTER_VERTICAL|wxLEFT, 5 );
+
+
+    bSizer1881->Add( bSizer292, 0, wxTOP, 5 );
+
 
-    m_buttonResetDialogs = new zen::BitmapTextButton( m_panel39, wxID_ANY, _("dummy"), wxDefaultPosition, wxSize( -1, -1 ), 0 );
-    bSizer1881->Add( m_buttonResetDialogs, 0, wxALL, 5 );
+    bSizer293->Add( bSizer1881, 0, wxTOP|wxBOTTOM|wxRIGHT, 5 );
 
 
-    bSizer186->Add( bSizer1881, 0, wxALL|wxALIGN_CENTER_VERTICAL, 5 );
+    bSizer186->Add( bSizer293, 0, wxALL, 5 );
 
 
     bSizer166->Add( bSizer186, 0, wxEXPAND, 5 );
@@ -4405,32 +4424,78 @@ OptionsDlgGenerated::OptionsDlgGenerated( wxWindow* parent, wxWindowID id, const
     bSizer258 = new wxBoxSizer( wxHORIZONTAL );
 
     m_bitmapLogFile = new wxStaticBitmap( m_panel39, wxID_ANY, wxNullBitmap, wxDefaultPosition, wxDefaultSize, 0 );
-    bSizer258->Add( m_bitmapLogFile, 0, wxALIGN_CENTER_VERTICAL, 5 );
+    bSizer258->Add( m_bitmapLogFile, 0, wxALIGN_CENTER_VERTICAL|wxALL, 5 );
 
     m_staticText163 = new wxStaticText( m_panel39, wxID_ANY, _("Default log path:"), wxDefaultPosition, wxDefaultSize, 0 );
     m_staticText163->Wrap( -1 );
-    bSizer258->Add( m_staticText163, 0, wxALIGN_CENTER_VERTICAL|wxRIGHT|wxLEFT, 5 );
+    bSizer258->Add( m_staticText163, 0, wxALIGN_CENTER_VERTICAL|wxTOP|wxBOTTOM|wxRIGHT, 5 );
 
     m_hyperlinkLogFolder = new wxHyperlinkCtrl( m_panel39, wxID_ANY, _("dummy"), wxEmptyString, wxDefaultPosition, wxDefaultSize, wxHL_DEFAULT_STYLE );
-    bSizer258->Add( m_hyperlinkLogFolder, 0, wxALIGN_CENTER_VERTICAL|wxLEFT, 5 );
+    bSizer258->Add( m_hyperlinkLogFolder, 0, wxALIGN_CENTER_VERTICAL|wxTOP|wxBOTTOM|wxRIGHT, 5 );
 
 
-    bSizer259->Add( bSizer258, 0, wxALL|wxEXPAND, 5 );
+    bSizer259->Add( bSizer258, 0, wxALL, 5 );
+
+    wxBoxSizer* bSizer299;
+    bSizer299 = new wxBoxSizer( wxVERTICAL );
+
+    m_staticline83 = new wxStaticLine( m_panel39, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxLI_HORIZONTAL );
+    bSizer299->Add( m_staticline83, 0, wxEXPAND, 5 );
+
+    wxBoxSizer* bSizer297;
+    bSizer297 = new wxBoxSizer( wxHORIZONTAL );
+
+    m_staticline82 = new wxStaticLine( m_panel39, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxLI_VERTICAL );
+    bSizer297->Add( m_staticline82, 0, wxEXPAND, 5 );
 
     wxBoxSizer* bSizer282;
     bSizer282 = new wxBoxSizer( wxHORIZONTAL );
 
     m_checkBoxLogFilesMaxAge = new wxCheckBox( m_panel39, wxID_ANY, _("&Delete logs after x days:"), wxDefaultPosition, wxDefaultSize, 0 );
-    bSizer282->Add( m_checkBoxLogFilesMaxAge, 0, wxALIGN_CENTER_VERTICAL|wxRIGHT, 5 );
+    bSizer282->Add( m_checkBoxLogFilesMaxAge, 0, wxALIGN_CENTER_VERTICAL|wxALL, 5 );
 
     m_spinCtrlLogFilesMaxAge = new wxSpinCtrl( m_panel39, wxID_ANY, wxEmptyString, wxDefaultPosition, wxSize( -1, -1 ), wxSP_ARROW_KEYS, 1, 2000000000, 1 );
-    bSizer282->Add( m_spinCtrlLogFilesMaxAge, 0, wxALIGN_CENTER_VERTICAL, 5 );
+    bSizer282->Add( m_spinCtrlLogFilesMaxAge, 0, wxALIGN_CENTER_VERTICAL|wxTOP|wxBOTTOM|wxRIGHT, 5 );
+
+
+    bSizer297->Add( bSizer282, 0, wxALIGN_CENTER_VERTICAL|wxALL, 5 );
+
+    m_staticline81 = new wxStaticLine( m_panel39, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxLI_VERTICAL );
+    bSizer297->Add( m_staticline81, 0, wxEXPAND, 5 );
+
+    wxBoxSizer* bSizer296;
+    bSizer296 = new wxBoxSizer( wxHORIZONTAL );
+
+    m_staticText184 = new wxStaticText( m_panel39, wxID_ANY, _("Log file format:"), wxDefaultPosition, wxDefaultSize, 0 );
+    m_staticText184->Wrap( -1 );
+    bSizer296->Add( m_staticText184, 0, wxALIGN_CENTER_VERTICAL|wxALL, 5 );
+
+    wxFlexGridSizer* fgSizer251;
+    fgSizer251 = new wxFlexGridSizer( 0, 1, 5, 0 );
+    fgSizer251->SetFlexibleDirection( wxBOTH );
+    fgSizer251->SetNonFlexibleGrowMode( wxFLEX_GROWMODE_SPECIFIED );
 
+    m_radioBtnLogHtml = new wxRadioButton( m_panel39, wxID_ANY, _("&HTML"), wxDefaultPosition, wxDefaultSize, wxRB_GROUP );
+    m_radioBtnLogHtml->SetValue( true );
+    fgSizer251->Add( m_radioBtnLogHtml, 0, wxEXPAND, 5 );
 
-    bSizer259->Add( bSizer282, 0, wxALL, 5 );
+    m_radioBtnLogText = new wxRadioButton( m_panel39, wxID_ANY, _("&Plain text"), wxDefaultPosition, wxDefaultSize, 0 );
+    fgSizer251->Add( m_radioBtnLogText, 0, wxEXPAND, 5 );
 
 
-    bSizer166->Add( bSizer259, 0, wxALL|wxEXPAND, 5 );
+    bSizer296->Add( fgSizer251, 0, wxTOP|wxBOTTOM|wxRIGHT, 5 );
+
+
+    bSizer297->Add( bSizer296, 0, wxALIGN_CENTER_VERTICAL|wxALL, 5 );
+
+
+    bSizer299->Add( bSizer297, 0, 0, 5 );
+
+
+    bSizer259->Add( bSizer299, 0, wxALIGN_RIGHT|wxLEFT, 15 );
+
+
+    bSizer166->Add( bSizer259, 0, wxEXPAND, 5 );
 
     m_staticline361 = new wxStaticLine( m_panel39, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxLI_HORIZONTAL );
     bSizer166->Add( m_staticline361, 0, wxEXPAND, 5 );
@@ -4438,33 +4503,38 @@ OptionsDlgGenerated::OptionsDlgGenerated( wxWindow* parent, wxWindowID id, const
     wxBoxSizer* bSizer288;
     bSizer288 = new wxBoxSizer( wxVERTICAL );
 
-    wxBoxSizer* bSizer291;
-    bSizer291 = new wxBoxSizer( wxHORIZONTAL );
+    wxBoxSizer* bSizer300;
+    bSizer300 = new wxBoxSizer( wxHORIZONTAL );
 
     m_bitmapNotificationSounds = new wxStaticBitmap( m_panel39, wxID_ANY, wxNullBitmap, wxDefaultPosition, wxDefaultSize, 0 );
-    bSizer291->Add( m_bitmapNotificationSounds, 0, wxALIGN_CENTER_VERTICAL, 5 );
+    bSizer300->Add( m_bitmapNotificationSounds, 0, wxALIGN_CENTER_VERTICAL, 5 );
 
     m_staticText851 = new wxStaticText( m_panel39, wxID_ANY, _("Notification sounds:"), wxDefaultPosition, wxDefaultSize, 0 );
     m_staticText851->Wrap( -1 );
-    bSizer291->Add( m_staticText851, 0, wxALIGN_CENTER_VERTICAL|wxLEFT, 5 );
+    bSizer300->Add( m_staticText851, 0, wxALIGN_CENTER_VERTICAL|wxLEFT, 5 );
+
 
+    bSizer288->Add( bSizer300, 0, wxTOP|wxRIGHT|wxLEFT, 5 );
 
-    bSizer288->Add( bSizer291, 0, wxALL, 5 );
+    wxBoxSizer* bSizer301;
+    bSizer301 = new wxBoxSizer( wxHORIZONTAL );
 
-    ffgSizer11 = new wxFlexGridSizer( 0, 4, 0, 0 );
-    ffgSizer11->AddGrowableCol( 3 );
+
+    bSizer301->Add( 15, 0, 0, 0, 5 );
+
+    ffgSizer11 = new wxFlexGridSizer( 0, 3, 0, 5 );
+    ffgSizer11->AddGrowableCol( 2 );
     ffgSizer11->SetFlexibleDirection( wxBOTH );
     ffgSizer11->SetNonFlexibleGrowMode( wxFLEX_GROWMODE_SPECIFIED );
 
-
-    ffgSizer11->Add( 10, 0, 0, 0, 5 );
+    m_bitmapCompareDone = new wxStaticBitmap( m_panel39, wxID_ANY, wxNullBitmap, wxDefaultPosition, wxDefaultSize, 0 );
+    ffgSizer11->Add( m_bitmapCompareDone, 0, wxALIGN_CENTER_VERTICAL, 5 );
 
     m_staticText171 = new wxStaticText( m_panel39, wxID_ANY, _("Comparison finished:"), wxDefaultPosition, wxDefaultSize, 0 );
     m_staticText171->Wrap( -1 );
-    ffgSizer11->Add( m_staticText171, 0, wxALIGN_CENTER_VERTICAL|wxALIGN_RIGHT, 5 );
+    m_staticText171->SetForegroundColour( wxSystemSettings::GetColour( wxSYS_COLOUR_GRAYTEXT ) );
 
-    m_bitmapCompareDone = new wxStaticBitmap( m_panel39, wxID_ANY, wxNullBitmap, wxDefaultPosition, wxDefaultSize, 0 );
-    ffgSizer11->Add( m_bitmapCompareDone, 0, wxALIGN_CENTER_VERTICAL|wxRIGHT|wxLEFT, 5 );
+    ffgSizer11->Add( m_staticText171, 0, wxALIGN_CENTER_VERTICAL, 5 );
 
     wxBoxSizer* bSizer290;
     bSizer290 = new wxBoxSizer( wxHORIZONTAL );
@@ -4483,15 +4553,14 @@ OptionsDlgGenerated::OptionsDlgGenerated( wxWindow* parent, wxWindowID id, const
 
     ffgSizer11->Add( bSizer290, 0, wxALIGN_CENTER_VERTICAL|wxEXPAND, 5 );
 
-
-    ffgSizer11->Add( 0, 0, 0, 0, 5 );
+    m_bitmapSyncDone = new wxStaticBitmap( m_panel39, wxID_ANY, wxNullBitmap, wxDefaultPosition, wxDefaultSize, 0 );
+    ffgSizer11->Add( m_bitmapSyncDone, 0, wxALIGN_CENTER_VERTICAL, 5 );
 
     m_staticText1711 = new wxStaticText( m_panel39, wxID_ANY, _("Synchronization finished:"), wxDefaultPosition, wxDefaultSize, 0 );
     m_staticText1711->Wrap( -1 );
-    ffgSizer11->Add( m_staticText1711, 0, wxALIGN_CENTER_VERTICAL|wxALIGN_RIGHT, 5 );
+    m_staticText1711->SetForegroundColour( wxSystemSettings::GetColour( wxSYS_COLOUR_GRAYTEXT ) );
 
-    m_bitmapSyncDone = new wxStaticBitmap( m_panel39, wxID_ANY, wxNullBitmap, wxDefaultPosition, wxDefaultSize, 0 );
-    ffgSizer11->Add( m_bitmapSyncDone, 0, wxALIGN_CENTER_VERTICAL|wxRIGHT|wxLEFT, 5 );
+    ffgSizer11->Add( m_staticText1711, 0, wxALIGN_CENTER_VERTICAL, 5 );
 
     wxBoxSizer* bSizer2901;
     bSizer2901 = new wxBoxSizer( wxHORIZONTAL );
@@ -4511,10 +4580,13 @@ OptionsDlgGenerated::OptionsDlgGenerated( wxWindow* parent, wxWindowID id, const
     ffgSizer11->Add( bSizer2901, 0, wxALIGN_CENTER_VERTICAL|wxEXPAND, 5 );
 
 
-    bSizer288->Add( ffgSizer11, 0, wxEXPAND|wxBOTTOM|wxRIGHT|wxLEFT, 5 );
+    bSizer301->Add( ffgSizer11, 1, wxALL, 5 );
+
+
+    bSizer288->Add( bSizer301, 0, wxEXPAND, 5 );
 
 
-    bSizer166->Add( bSizer288, 0, wxALL|wxEXPAND, 5 );
+    bSizer166->Add( bSizer288, 0, wxEXPAND|wxALL, 5 );
 
     m_staticline3611 = new wxStaticLine( m_panel39, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxLI_HORIZONTAL );
     bSizer166->Add( m_staticline3611, 0, wxEXPAND, 5 );
@@ -4680,7 +4752,7 @@ OptionsDlgGenerated::OptionsDlgGenerated( wxWindow* parent, wxWindowID id, const
 
     // Connect Events
     this->Connect( wxEVT_CLOSE_WINDOW, wxCloseEventHandler( OptionsDlgGenerated::OnClose ) );
-    m_buttonResetDialogs->Connect( wxEVT_COMMAND_BUTTON_CLICKED, wxCommandEventHandler( OptionsDlgGenerated::OnResetDialogs ), NULL, this );
+    m_buttonRestoreDialogs->Connect( wxEVT_COMMAND_BUTTON_CLICKED, wxCommandEventHandler( OptionsDlgGenerated::OnRestoreDialogs ), NULL, this );
     m_hyperlinkLogFolder->Connect( wxEVT_COMMAND_HYPERLINK, wxHyperlinkEventHandler( OptionsDlgGenerated::OnShowLogFolder ), NULL, this );
     m_checkBoxLogFilesMaxAge->Connect( wxEVT_COMMAND_CHECKBOX_CLICKED, wxCommandEventHandler( OptionsDlgGenerated::OnToggleLogfilesLimit ), NULL, this );
     m_textCtrlSoundPathCompareDone->Connect( wxEVT_COMMAND_TEXT_UPDATED, wxCommandEventHandler( OptionsDlgGenerated::OnChangeSoundFilePath ), NULL, this );
@@ -4691,7 +4763,7 @@ OptionsDlgGenerated::OptionsDlgGenerated( wxWindow* parent, wxWindowID id, const
     m_bpButtonPlaySyncDone->Connect( wxEVT_COMMAND_BUTTON_CLICKED, wxCommandEventHandler( OptionsDlgGenerated::OnPlaySyncDone ), NULL, this );
     m_bpButtonAddRow->Connect( wxEVT_COMMAND_BUTTON_CLICKED, wxCommandEventHandler( OptionsDlgGenerated::OnAddRow ), NULL, this );
     m_bpButtonRemoveRow->Connect( wxEVT_COMMAND_BUTTON_CLICKED, wxCommandEventHandler( OptionsDlgGenerated::OnRemoveRow ), NULL, this );
-    m_hyperlink17->Connect( wxEVT_COMMAND_HYPERLINK, wxHyperlinkEventHandler( OptionsDlgGenerated::OnHelpShowExamples ), NULL, this );
+    m_hyperlink17->Connect( wxEVT_COMMAND_HYPERLINK, wxHyperlinkEventHandler( OptionsDlgGenerated::OnHelpExternalApps ), NULL, this );
     m_buttonDefault->Connect( wxEVT_COMMAND_BUTTON_CLICKED, wxCommandEventHandler( OptionsDlgGenerated::OnDefault ), NULL, this );
     m_buttonOkay->Connect( wxEVT_COMMAND_BUTTON_CLICKED, wxCommandEventHandler( OptionsDlgGenerated::OnOkay ), NULL, this );
     m_buttonCancel->Connect( wxEVT_COMMAND_BUTTON_CLICKED, wxCommandEventHandler( OptionsDlgGenerated::OnCancel ), NULL, this );
diff --git a/FreeFileSync/Source/ui/gui_generated.h b/FreeFileSync/Source/ui/gui_generated.h
index 761dfb15..07867a58 100644
--- a/FreeFileSync/Source/ui/gui_generated.h
+++ b/FreeFileSync/Source/ui/gui_generated.h
@@ -260,8 +260,8 @@ public:
     wxPanel* m_panelTopRight;
     fff::FolderHistoryBox* m_folderPathRight;
     wxBitmapButton* m_bpButtonSelectAltFolderRight;
-    wxStaticBitmap* m_bitmapLogStatus;
-    wxStaticText* m_staticTextLogStatus;
+    wxStaticBitmap* m_bitmapSyncResult;
+    wxStaticText* m_staticTextSyncResult;
     wxStaticText* m_staticTextProcessed;
     wxStaticText* m_staticTextRemaining;
     wxPanel* m_panelItemStats;
@@ -503,7 +503,7 @@ protected:
     virtual void OnToggleAutoRetry( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnHelpPerformance( wxHyperlinkEvent& event ) { event.Skip(); }
     virtual void OnChangeFilterOption( wxCommandEvent& event ) { event.Skip(); }
-    virtual void OnHelpShowExamples( wxHyperlinkEvent& event ) { event.Skip(); }
+    virtual void OnHelpFilterSettings( wxHyperlinkEvent& event ) { event.Skip(); }
     virtual void OnFilterReset( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnToggleLocalSyncSettings( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnSyncTwoWayDouble( wxMouseEvent& event ) { event.Skip(); }
@@ -528,10 +528,11 @@ protected:
     virtual void OnHelpVersioning( wxHyperlinkEvent& event ) { event.Skip(); }
     virtual void OnChanegVersioningStyle( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnToggleVersioningLimit( wxCommandEvent& event ) { event.Skip(); }
-    virtual void OnToggleMiscOption( wxCommandEvent& event ) { event.Skip(); }
+    virtual void OnToggleMiscEmail( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnEmailAlways( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnEmailErrorWarning( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnEmailErrorOnly( wxCommandEvent& event ) { event.Skip(); }
+    virtual void OnToggleMiscOption( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnOkay( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnCancel( wxCommandEvent& event ) { event.Skip(); }
 
@@ -1025,25 +1026,33 @@ protected:
     wxStaticText* m_staticText93;
     wxStaticText* m_staticText932;
     wxStaticLine* m_staticline39;
+    wxStaticBitmap* m_bitmapWarnings;
     wxStaticText* m_staticTextResetDialogs;
-    zen::BitmapTextButton* m_buttonResetDialogs;
+    wxButton* m_buttonRestoreDialogs;
+    wxStaticText* m_staticTextAllDialogsShown;
     wxStaticLine* m_staticline191;
     wxStaticBitmap* m_bitmapLogFile;
     wxStaticText* m_staticText163;
     wxHyperlinkCtrl* m_hyperlinkLogFolder;
+    wxStaticLine* m_staticline83;
+    wxStaticLine* m_staticline82;
     wxCheckBox* m_checkBoxLogFilesMaxAge;
     wxSpinCtrl* m_spinCtrlLogFilesMaxAge;
+    wxStaticLine* m_staticline81;
+    wxStaticText* m_staticText184;
+    wxRadioButton* m_radioBtnLogHtml;
+    wxRadioButton* m_radioBtnLogText;
     wxStaticLine* m_staticline361;
     wxStaticBitmap* m_bitmapNotificationSounds;
     wxStaticText* m_staticText851;
     wxFlexGridSizer* ffgSizer11;
-    wxStaticText* m_staticText171;
     wxStaticBitmap* m_bitmapCompareDone;
+    wxStaticText* m_staticText171;
     wxTextCtrl* m_textCtrlSoundPathCompareDone;
     wxButton* m_buttonSelectSoundCompareDone;
     wxBitmapButton* m_bpButtonPlayCompareDone;
-    wxStaticText* m_staticText1711;
     wxStaticBitmap* m_bitmapSyncDone;
+    wxStaticText* m_staticText1711;
     wxTextCtrl* m_textCtrlSoundPathSyncDone;
     wxButton* m_buttonSelectSoundSyncDone;
     wxBitmapButton* m_bpButtonPlaySyncDone;
@@ -1069,7 +1078,7 @@ protected:
 
     // Virtual event handlers, overide them in your derived class
     virtual void OnClose( wxCloseEvent& event ) { event.Skip(); }
-    virtual void OnResetDialogs( wxCommandEvent& event ) { event.Skip(); }
+    virtual void OnRestoreDialogs( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnShowLogFolder( wxHyperlinkEvent& event ) { event.Skip(); }
     virtual void OnToggleLogfilesLimit( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnChangeSoundFilePath( wxCommandEvent& event ) { event.Skip(); }
@@ -1079,7 +1088,7 @@ protected:
     virtual void OnPlaySyncDone( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnAddRow( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnRemoveRow( wxCommandEvent& event ) { event.Skip(); }
-    virtual void OnHelpShowExamples( wxHyperlinkEvent& event ) { event.Skip(); }
+    virtual void OnHelpExternalApps( wxHyperlinkEvent& event ) { event.Skip(); }
     virtual void OnDefault( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnOkay( wxCommandEvent& event ) { event.Skip(); }
     virtual void OnCancel( wxCommandEvent& event ) { event.Skip(); }
diff --git a/FreeFileSync/Source/ui/gui_status_handler.cpp b/FreeFileSync/Source/ui/gui_status_handler.cpp
index 8adf1f89..6ad01cd2 100644
--- a/FreeFileSync/Source/ui/gui_status_handler.cpp
+++ b/FreeFileSync/Source/ui/gui_status_handler.cpp
@@ -11,9 +11,9 @@
 #include <wx/wupdlock.h>
 #include <wx+/popup_dlg.h>
 #include "main_dlg.h"
-#include "../base/log_file.h"
-#include "../base/resolve_path.h"
 #include "../afs/concrete.h"
+#include "../base/resolve_path.h"
+#include "../log_file.h"
 
 using namespace zen;
 using namespace fff;
@@ -148,9 +148,11 @@ StatusHandlerTemporaryPanel::Result StatusHandlerTemporaryPanel::reportResults()
             errorLog_.logMsg(_("Stopped"), MSG_TYPE_ERROR); //= user cancel; *not* a MSG_TYPE_FATAL_ERROR!
             return SyncResult::aborted;
         }
-        else if (errorLog_.getItemCount(MSG_TYPE_ERROR | MSG_TYPE_FATAL_ERROR) > 0)
+
+        const ErrorLog::Stats logCount = errorLog_.getStats();
+        if (logCount.error + logCount.fatal > 0)
             return SyncResult::finishedError;
-        else if (errorLog_.getItemCount(MSG_TYPE_WARNING) > 0)
+        else if (logCount.warning > 0)
             return SyncResult::finishedWarning;
         else
             return SyncResult::finishedSuccess;
@@ -228,7 +230,7 @@ ProcessCallback::Response StatusHandlerTemporaryPanel::reportError(const std::ws
     if (retryNumber < automaticRetryCount_)
     {
         errorLog_.logMsg(msg + L"\n-> " + _("Automatic retry"), MSG_TYPE_INFO);
-        delayAndCountDown(_("Automatic retry") + (automaticRetryCount_ <= 1 ? L"" :  L" " + numberTo<std::wstring>(retryNumber + 1) + L"/" + numberTo<std::wstring>(automaticRetryCount_)),
+        delayAndCountDown(_("Automatic retry") + (automaticRetryCount_ <= 1 ? L"" :  L' ' + numberTo<std::wstring>(retryNumber + 1) + L"/" + numberTo<std::wstring>(automaticRetryCount_)),
         automaticRetryDelay_, [&](const std::wstring& statusMsg) { this->updateStatus(_("Error") + L": " + statusMsg); }); //throw AbortProcess
         return ProcessCallback::retry;
     }
@@ -354,8 +356,9 @@ StatusHandlerFloatingDialog::~StatusHandlerFloatingDialog()
 
 
 StatusHandlerFloatingDialog::Result StatusHandlerFloatingDialog::reportResults(const Zstring& postSyncCommand, PostSyncCondition postSyncCondition,
-                                                                               const Zstring& altLogFolderPathPhrase, int logfilesMaxAgeDays, const std::set<AbstractPath>& logFilePathsToKeep,
-                                                                               const Zstring& emailNotifyAddress, ResultsNotification emailNotifyCondition)
+                                                                               const Zstring& altLogFolderPathPhrase, int logfilesMaxAgeDays, LogFileFormat logFormat,
+                                                                               const std::set<AbstractPath>& logFilePathsToKeep,
+                                                                               const std::string& emailNotifyAddress, ResultsNotification emailNotifyCondition)
 {
     const auto totalTime = std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock::now() - startTime_);
 
@@ -369,9 +372,11 @@ StatusHandlerFloatingDialog::Result StatusHandlerFloatingDialog::reportResults(c
             errorLog_.logMsg(_("Stopped"), MSG_TYPE_ERROR); //= user cancel; *not* a MSG_TYPE_FATAL_ERROR!
             return SyncResult::aborted;
         }
-        else if (errorLog_.getItemCount(MSG_TYPE_ERROR | MSG_TYPE_FATAL_ERROR) > 0)
+
+        const ErrorLog::Stats logCount = errorLog_.getStats();
+        if (logCount.error + logCount.fatal > 0)
             return SyncResult::finishedError;
-        else if (errorLog_.getItemCount(MSG_TYPE_WARNING) > 0)
+        else if (logCount.warning > 0)
             return SyncResult::finishedWarning;
 
         if (getStatsTotal() == ProgressStats())
@@ -389,7 +394,7 @@ StatusHandlerFloatingDialog::Result StatusHandlerFloatingDialog::reportResults(c
         totalTime
     };
 
-    const AbstractPath logFilePath = generateLogFilePath(summary, altLogFolderPathPhrase);
+    const AbstractPath logFilePath = generateLogFilePath(logFormat, summary, altLogFolderPathPhrase);
     //e.g. %AppData%\FreeFileSync\Logs\Backup FreeFileSync 2013-09-15 015052.123 [Error].log
 
     if (const Zstring cmdLine = trimCpy(postSyncCommand);
@@ -406,9 +411,8 @@ StatusHandlerFloatingDialog::Result StatusHandlerFloatingDialog::reportResults(c
                 //::wxSetEnv(L"logfile_path", AFS::getDisplayPath(logFilePath));
                 ////----------------------------------------------------------------------
                 const Zstring cmdLineExp = expandMacros(cmdLine);
-                const int exitCode = shellExecute(cmdLineExp, ExecutionType::sync, false /*hideConsole*/); //throw FileError
-                errorLog_.logMsg(_("Executing command:") + L" " + utfTo<std::wstring>(cmdLineExp) + L" [" + replaceCpy(_("Exit Code %x"), L"%x", numberTo<std::wstring>(exitCode)) + L']',
-                                 exitCode == 0 ? MSG_TYPE_INFO : MSG_TYPE_ERROR);
+                errorLog_.logMsg(_("Executing command:") + L' ' + utfTo<std::wstring>(cmdLineExp), MSG_TYPE_INFO);
+                shellExecute(cmdLineExp, ExecutionType::async, false /*hideConsole*/); //throw FileError
             }
             catch (const FileError& e) { errorLog_.logMsg(e.toString(), MSG_TYPE_ERROR); }
     }
@@ -416,7 +420,7 @@ StatusHandlerFloatingDialog::Result StatusHandlerFloatingDialog::reportResults(c
     //---------------------------- save log file ------------------------------
     auto notifyStatusNoThrow = [&](const std::wstring& msg) { try { updateStatus(msg); /*throw AbortProcess*/ } catch (AbortProcess&) {} };
 
-    if (const Zstring notifyEmail = trimCpy(emailNotifyAddress);
+    if (const std::string notifyEmail = trimCpy(emailNotifyAddress);
         !notifyEmail.empty())
     {
         if (getAbortStatus() && *getAbortStatus() == AbortTrigger::user)
@@ -437,7 +441,7 @@ StatusHandlerFloatingDialog::Result StatusHandlerFloatingDialog::reportResults(c
     try //create not before destruction: 1. avoid issues with FFS trying to sync open log file 2. include status in log file name without extra rename
     {
         //do NOT use tryReportingError()! saving log files should not be cancellable!
-        saveLogFile(logFilePath, summary, errorLog_, logfilesMaxAgeDays, logFilePathsToKeep, notifyStatusNoThrow); //throw FileError
+        saveLogFile(logFilePath, summary, errorLog_, logfilesMaxAgeDays, logFormat, logFilePathsToKeep, notifyStatusNoThrow); //throw FileError
     }
     catch (const FileError& e) { errorLog_.logMsg(e.toString(), MSG_TYPE_ERROR); }
 
@@ -566,7 +570,7 @@ ProcessCallback::Response StatusHandlerFloatingDialog::reportError(const std::ws
     if (retryNumber < automaticRetryCount_)
     {
         errorLog_.logMsg(msg + L"\n-> " + _("Automatic retry"), MSG_TYPE_INFO);
-        delayAndCountDown(_("Automatic retry") + (automaticRetryCount_ <= 1 ? L"" :  L" " + numberTo<std::wstring>(retryNumber + 1) + L"/" + numberTo<std::wstring>(automaticRetryCount_)),
+        delayAndCountDown(_("Automatic retry") + (automaticRetryCount_ <= 1 ? L"" :  L' ' + numberTo<std::wstring>(retryNumber + 1) + L"/" + numberTo<std::wstring>(automaticRetryCount_)),
         automaticRetryDelay_, [&](const std::wstring& statusMsg) { this->updateStatus(_("Error") + L": " + statusMsg); }); //throw AbortProcess
         return ProcessCallback::retry;
     }
diff --git a/FreeFileSync/Source/ui/gui_status_handler.h b/FreeFileSync/Source/ui/gui_status_handler.h
index 82903078..5f671a82 100644
--- a/FreeFileSync/Source/ui/gui_status_handler.h
+++ b/FreeFileSync/Source/ui/gui_status_handler.h
@@ -11,7 +11,7 @@
 #include <wx/event.h>
 #include "progress_indicator.h"
 #include "main_dlg.h"
-#include "../base/status_handler.h"
+#include "../status_handler.h"
 
 
 namespace fff
@@ -92,8 +92,8 @@ public:
         AbstractPath logFilePath;
     };
     Result reportResults(const Zstring& postSyncCommand, PostSyncCondition postSyncCondition,
-                         const Zstring& altLogFolderPathPhrase, int logfilesMaxAgeDays, const std::set<AbstractPath>& logFilePathsToKeep,
-                         const Zstring& emailNotifyAddress, ResultsNotification emailNotifyCondition); //noexcept!!
+                         const Zstring& altLogFolderPathPhrase, int logfilesMaxAgeDays, LogFileFormat logFormat, const std::set<AbstractPath>& logFilePathsToKeep,
+                         const std::string& emailNotifyAddress, ResultsNotification emailNotifyCondition); //noexcept!!
 
 private:
     SyncProgressDialog* progressDlg_; //managed to have the same lifetime as this handler!
diff --git a/FreeFileSync/Source/ui/log_panel.cpp b/FreeFileSync/Source/ui/log_panel.cpp
index 51cfa703..52322dc9 100644
--- a/FreeFileSync/Source/ui/log_panel.cpp
+++ b/FreeFileSync/Source/ui/log_panel.cpp
@@ -62,7 +62,7 @@ public:
     {
         time_t      time = 0;
         MessageType type = MSG_TYPE_INFO;
-        Zstringw    messageLine;
+        std::string_view messageLine;
         bool firstLine = false; //if LogEntry::message spans multiple rows
     };
 
@@ -73,10 +73,10 @@ public:
             const Line& line = viewRef_[row];
 
             LogEntryView output;
-            output.time = line.logIt_->time;
-            output.type = line.logIt_->type;
-            output.messageLine = extractLine(line.logIt_->message, line.rowNumber_);
-            output.firstLine = line.rowNumber_ == 0; //this is virtually always correct, unless first line of the original message is empty!
+            output.time = line.logIt->time;
+            output.type = line.logIt->type;
+            output.messageLine = extractLine(line.logIt->message, line.row);
+            output.firstLine = line.row == 0; //this is virtually always correct, unless first line of the original message is empty!
             return output;
         }
         return {};
@@ -89,13 +89,12 @@ public:
         for (auto it = log_.ref().begin(); it != log_.ref().end(); ++it)
             if (it->type & includedTypes)
             {
-                static_assert(std::is_same_v<GetCharTypeT<Zstringw>, wchar_t>);
-                assert(!startsWith(it->message, L'\n'));
+                assert(!startsWith(it->message, '\n'));
 
                 size_t rowNumber = 0;
                 bool lastCharNewline = true;
-                for (const wchar_t c : it->message)
-                    if (c == L'\n')
+                for (const char c : it->message)
+                    if (c == '\n')
                     {
                         if (!lastCharNewline) //do not reference empty lines!
                             viewRef_.emplace_back(it, rowNumber);
@@ -111,19 +110,19 @@ public:
     }
 
 private:
-    static Zstringw extractLine(const Zstringw& message, size_t textRow)
+    static std::string_view extractLine(const Zstringc& message, size_t textRow)
     {
         auto it1 = message.begin();
         for (;;)
         {
-            auto it2 = std::find_if(it1, message.end(), [](wchar_t c) { return c == L'\n'; });
+            auto it2 = std::find_if(it1, message.end(), [](char c) { return c == '\n'; });
             if (textRow == 0)
-                return it1 == message.end() ? Zstringw() : Zstringw(&*it1, it2 - it1); //must not dereference iterator pointing to "end"!
+                return makeStringView(it1, it2 - it1);
 
             if (it2 == message.end())
             {
                 assert(false);
-                return Zstringw();
+                return makeStringView(it1, 0);
             }
 
             it1 = it2 + 1; //skip newline
@@ -133,10 +132,10 @@ private:
 
     struct Line
     {
-        Line(ErrorLog::const_iterator logIt, size_t rowNumber) : logIt_(logIt), rowNumber_(rowNumber) {}
+        Line(ErrorLog::const_iterator it, size_t rowNum) : logIt(it), row(rowNum) {}
 
-        ErrorLog::const_iterator logIt_; //always bound!
-        size_t rowNumber_; //LogEntry::message may span multiple rows
+        ErrorLog::const_iterator logIt; //always bound!
+        size_t row; //LogEntry::message may span multiple rows
     };
 
     std::vector<Line> viewRef_; //partial view on log_
@@ -161,12 +160,12 @@ public:
 
     std::wstring getValue(size_t row, ColumnType colType) const override
     {
-        if (std::optional<MessageView::LogEntryView> entry = msgView_.getEntry(row))
+        if (const std::optional<MessageView::LogEntryView> entry = msgView_.getEntry(row))
             switch (static_cast<ColumnTypeLog>(colType))
             {
                 case ColumnTypeLog::time:
                     if (entry->firstLine)
-                        return formatTime<std::wstring>(FORMAT_TIME, getLocalTime(entry->time));
+                        return utfTo<std::wstring>(formatTime(formatTimeTag, getLocalTime(entry->time)));
                     break;
 
                 case ColumnTypeLog::category:
@@ -185,7 +184,7 @@ public:
                     break;
 
                 case ColumnTypeLog::text:
-                    return copyStringTo<std::wstring>(entry->messageLine);
+                    return utfTo<std::wstring>(entry->messageLine);
             }
         return std::wstring();
     }
@@ -277,7 +276,7 @@ public:
     {
         wxClientDC dc(&grid.getMainWin());
         dc.SetFont(grid.getMainWin().GetFont());
-        return 2 * getColumnGapLeft() + dc.GetTextExtent(formatTime<wxString>(FORMAT_TIME)).GetWidth();
+        return 2 * getColumnGapLeft() + dc.GetTextExtent(utfTo<wxString>(formatTime(formatTimeTag))).GetWidth();
     }
 
     static int getColumnCategoryDefaultWidth()
@@ -353,9 +352,7 @@ void LogPanel::setLog(const std::shared_ptr<const ErrorLog>& log)
         return makeSharedRef<const ErrorLog>(std::move(dummyLog));
     }();
 
-    const int errorCount   = newLog.ref().getItemCount(MSG_TYPE_ERROR | MSG_TYPE_FATAL_ERROR);
-    const int warningCount = newLog.ref().getItemCount(MSG_TYPE_WARNING);
-    const int infoCount    = newLog.ref().getItemCount(MSG_TYPE_INFO);
+    const ErrorLog::Stats logCount = newLog.ref().getStats();
 
     auto initButton = [](ToggleButton& btn, const wchar_t* imgName, const wxString& tooltip)
     {
@@ -363,17 +360,17 @@ void LogPanel::setLog(const std::shared_ptr<const ErrorLog>& log)
         btn.SetToolTip(tooltip);
     };
 
-    initButton(*m_bpButtonErrors,   L"msg_error",   _("Error"  ) + L" (" + formatNumber(errorCount)   + L")");
-    initButton(*m_bpButtonWarnings, L"msg_warning", _("Warning") + L" (" + formatNumber(warningCount) + L")");
-    initButton(*m_bpButtonInfo,     L"msg_info",    _("Info"   ) + L" (" + formatNumber(infoCount)    + L")");
+    initButton(*m_bpButtonErrors,   L"msg_error",   _("Error"  ) + L" (" + formatNumber(logCount.error + logCount.fatal) + L")");
+    initButton(*m_bpButtonWarnings, L"msg_warning", _("Warning") + L" (" + formatNumber(logCount.warning               ) + L")");
+    initButton(*m_bpButtonInfo,     L"msg_info",    _("Info"   ) + L" (" + formatNumber(logCount.info                  ) + L")");
 
     m_bpButtonErrors  ->setActive(true);
     m_bpButtonWarnings->setActive(true);
-    m_bpButtonInfo    ->setActive(errorCount + warningCount == 0);
+    m_bpButtonInfo    ->setActive(logCount.warning + logCount.error + logCount.fatal == 0);
 
-    m_bpButtonErrors  ->Show(errorCount   != 0);
-    m_bpButtonWarnings->Show(warningCount != 0);
-    m_bpButtonInfo    ->Show(infoCount    != 0);
+    m_bpButtonErrors  ->Show(logCount.error + logCount.fatal != 0);
+    m_bpButtonWarnings->Show(logCount.warning != 0);
+    m_bpButtonInfo    ->Show(logCount.info    != 0);
 
     m_gridMessages->setDataProvider(std::make_shared<GridDataMessages>(newLog));
 
@@ -385,7 +382,7 @@ MessageView& LogPanel::getDataView()
 {
     if (auto* prov = dynamic_cast<GridDataMessages*>(m_gridMessages->getDataProvider()))
         return prov->getDataView();
-    throw std::runtime_error(std::string(__FILE__) + "[" + numberTo<std::string>(__LINE__) + "] m_gridMessages was not initialized.");
+    throw std::runtime_error(std::string(__FILE__) + '[' + numberTo<std::string>(__LINE__) + "] m_gridMessages was not initialized.");
 }
 
 
@@ -540,7 +537,7 @@ void LogPanel::copySelectionToClipboard()
 {
     try
     {
-        Zstringw clipboardString; //guaranteed exponential growth, unlike wxString
+        std::wstring clipBuf; //guaranteed exponential growth, unlike wxString
 
         if (auto prov = m_gridMessages->getDataProvider())
         {
@@ -552,24 +549,24 @@ void LogPanel::copySelectionToClipboard()
                     std::for_each(colAttr.begin(), --colAttr.end(),
                                   [&](const Grid::ColAttributes& ca)
                     {
-                        clipboardString += copyStringTo<Zstringw>(prov->getValue(row, ca.type));
-                        clipboardString += L'\t';
+                        clipBuf += prov->getValue(row, ca.type);
+                        clipBuf += L'\t';
                     });
-                    clipboardString += copyStringTo<Zstringw>(prov->getValue(row, colAttr.back().type));
-                    clipboardString += L'\n';
+                    clipBuf += prov->getValue(row, colAttr.back().type);
+                    clipBuf += L'\n';
                 }
         }
 
         //finally write to clipboard
-        if (!clipboardString.empty())
+        if (!clipBuf.empty())
             if (wxClipboard::Get()->Open())
             {
                 ZEN_ON_SCOPE_EXIT(wxClipboard::Get()->Close());
-                wxClipboard::Get()->SetData(new wxTextDataObject(copyStringTo<wxString>(clipboardString))); //ownership passed
+                wxClipboard::Get()->SetData(new wxTextDataObject(std::move(clipBuf))); //ownership passed
             }
     }
     catch (const std::bad_alloc& e)
     {
-        showNotificationDialog(nullptr, DialogInfoType::error, PopupDialogCfg().setMainInstructions(_("Out of memory.") + L" " + utfTo<std::wstring>(e.what())));
+        showNotificationDialog(nullptr, DialogInfoType::error, PopupDialogCfg().setMainInstructions(_("Out of memory.") + L' ' + utfTo<std::wstring>(e.what())));
     }
 }
diff --git a/FreeFileSync/Source/ui/main_dlg.cpp b/FreeFileSync/Source/ui/main_dlg.cpp
index d6fb64d4..4dcad8b3 100644
--- a/FreeFileSync/Source/ui/main_dlg.cpp
+++ b/FreeFileSync/Source/ui/main_dlg.cpp
@@ -44,10 +44,10 @@
 #include "../base/synchronization.h"
 #include "../base/algorithm.h"
 #include "../base/resolve_path.h"
-#include "../base/ffs_paths.h"
-#include "../base/help_provider.h"
 #include "../base/lock_holder.h"
-#include "../base/localization.h"
+#include "../ffs_paths.h"
+#include "../help_provider.h"
+#include "../localization.h"
 #include "../version/version.h"
 
 using namespace zen;
@@ -82,8 +82,8 @@ bool acceptDialogFileDrop(const std::vector<Zstring>& shellItemPaths)
     return std::any_of(shellItemPaths.begin(), shellItemPaths.end(), [](const Zstring& shellItemPath)
     {
         const Zstring ext = getFileExtension(shellItemPath);
-        return equalAsciiNoCase(ext, Zstr("ffs_gui")) ||
-               equalAsciiNoCase(ext, Zstr("ffs_batch"));
+        return equalAsciiNoCase(ext, "ffs_gui") ||
+               equalAsciiNoCase(ext, "ffs_batch");
     });
 }
 
@@ -324,8 +324,8 @@ void MainDialog::create(const Zstring& globalConfigFilePath)
     //add default exclusion filter: this is only ever relevant when creating new configurations!
     //a default XmlGuiConfig does not need these user-specific exclusions!
     Zstring& excludeFilter = guiCfg.mainCfg.globalFilter.excludeFilter;
-    if (!excludeFilter.empty() && !endsWith(excludeFilter, Zstr("\n")))
-        excludeFilter += Zstr("\n");
+    if (!excludeFilter.empty() && !endsWith(excludeFilter, Zstr('\n')))
+        excludeFilter += Zstr('\n');
     excludeFilter += globalSettings.gui.defaultExclusionFilter;
 
     if (!cfgFilePaths.empty())
@@ -463,7 +463,7 @@ MainDialog::MainDialog(const Zstring& globalConfigFilePath,
     const wxBitmap& bmpDir  = IconBuffer::genericDirIcon (IconBuffer::SIZE_SMALL);
 
     //init log panel
-    setRelativeFontSize(*m_staticTextLogStatus, 1.5);
+    setRelativeFontSize(*m_staticTextSyncResult, 1.5);
     const wxBitmap& bmpTime = getResourceImage(L"cmp_file_time_sicon");
     m_bitmapItemStat->SetBitmap(bmpFile);
     m_bitmapTimeStat->SetBitmap(bmpTime);
@@ -701,7 +701,7 @@ MainDialog::MainDialog(const Zstring& globalConfigFilePath,
         menu->Append(newItem); //pass ownership
 
         const std::wstring blackStar = utfTo<std::wstring>("\xE2\x98\x85"); //"BLACK STAR"
-        m_menubar->Append(menu, blackStar + L" " + replaceCpy(_("FreeFileSync %x is available!"), L"%x", utfTo<std::wstring>(globalSettings.gui.lastOnlineVersion)) + L" " + blackStar);
+        m_menubar->Append(menu, blackStar + L' ' + replaceCpy(_("FreeFileSync %x is available!"), L"%x", utfTo<std::wstring>(globalSettings.gui.lastOnlineVersion)) + L' ' + blackStar);
     }
 
 
@@ -1246,7 +1246,7 @@ void MainDialog::copySelectionToClipboard(const std::vector<const Grid*>& gridRe
     try
     {
         //perf: wxString doesn't model exponential growth and is unsuitable for large data sets
-        Zstringw clipboardString;
+        std::wstring clipBuf;
 
         for (const Grid* grid : gridRefs)
             if (auto prov = grid->getDataProvider())
@@ -1258,23 +1258,24 @@ void MainDialog::copySelectionToClipboard(const std::vector<const Grid*>& gridRe
                     {
                         std::for_each(colAttr.begin(), colAttr.end() - 1, [&](const Grid::ColAttributes& ca)
                         {
-                            clipboardString += copyStringTo<Zstringw>(prov->getValue(row, ca.type));
-                            clipboardString += L'\t';
+                            clipBuf += prov->getValue(row, ca.type);
+                            clipBuf += L'\t';
                         });
-                        clipboardString += copyStringTo<Zstringw>(prov->getValue(row, colAttr.back().type));
-                        clipboardString += L'\n';
+                        clipBuf += prov->getValue(row, colAttr.back().type);
+                        clipBuf += L'\n';
                     }
             }
 
-        if (wxClipboard::Get()->Open())
-        {
-            ZEN_ON_SCOPE_EXIT(wxClipboard::Get()->Close());
-            wxClipboard::Get()->SetData(new wxTextDataObject(copyStringTo<wxString>(clipboardString))); //ownership passed
-        }
+        if (!clipBuf.empty())
+            if (wxClipboard::Get()->Open())
+            {
+                ZEN_ON_SCOPE_EXIT(wxClipboard::Get()->Close());
+                wxClipboard::Get()->SetData(new wxTextDataObject(std::move(clipBuf))); //ownership passed
+            }
     }
     catch (const std::bad_alloc& e)
     {
-        showNotificationDialog(this, DialogInfoType::error, PopupDialogCfg().setMainInstructions(_("Out of memory.") + L" " + utfTo<std::wstring>(e.what())));
+        showNotificationDialog(this, DialogInfoType::error, PopupDialogCfg().setMainInstructions(_("Out of memory.") + L' ' + utfTo<std::wstring>(e.what())));
     }
 }
 
@@ -2403,7 +2404,7 @@ void MainDialog::onMainGridContextRim(bool leftSide, GridClickEvent& event)
             //translate default external apps on the fly: 1. "open in explorer" 2. "start directly"
             wxString description = translate(it->description);
             if (description.empty())
-                description = L" "; //wxWidgets doesn't like empty labels
+                description = L' '; //wxWidgets doesn't like empty labels
 
             auto openApp = [this, command = it->cmdLine, leftSide, &selectionLeft, &selectionRight] { openExternalApplication(command, leftSide, selectionLeft, selectionRight); };
 
@@ -2450,7 +2451,7 @@ void MainDialog::addFilterPhrase(const Zstring& phrase, bool include, bool requi
     {
         trim(filterString, false, true, [](Zchar c) { return c == FILTER_ITEM_SEPARATOR || c == Zstr('\n') || c == Zstr(' '); });
         if (!filterString.empty())
-            filterString += Zstr("\n");
+            filterString += Zstr('\n');
         filterString += phrase;
     }
     else
@@ -2460,9 +2461,9 @@ void MainDialog::addFilterPhrase(const Zstring& phrase, bool include, bool requi
         if (filterString.empty())
             ;
         else if (endsWith(filterString, FILTER_ITEM_SEPARATOR))
-            filterString += Zstr(" ");
+            filterString += Zstr(' ');
         else
-            filterString += Zstr("\n");
+            filterString += Zstr('\n');
 
         filterString += phrase + Zstr(' ') + FILTER_ITEM_SEPARATOR; //append FILTER_ITEM_SEPARATOR to 'mark' that next extension exclude should write to same line
     }
@@ -2506,7 +2507,7 @@ void MainDialog::filterItems(const std::vector<FileSystemObject*>& selection, bo
             FileSystemObject* fsObj = *it;
 
             if (it != selection.begin())
-                phrase += Zstr("\n");
+                phrase += Zstr('\n');
 
             //#pragma warning(suppress: 6011) -> fsObj bound in this context!
             phrase += FILE_NAME_SEPARATOR + fsObj->getRelativePathAny();
@@ -2832,7 +2833,7 @@ void MainDialog::updateUnsavedCfgStatus()
     std::vector<std::wstring> jobNames;
     for (const Zstring& cfgFilePath : activeConfigFiles_)
         jobNames.push_back(equalNativePath(cfgFilePath, lastRunConfigPath_) ?
-                           L"[" + _("Last session") + L"]" :
+                           L'[' + _("Last session") + L']' :
                            extractJobName(cfgFilePath));
 
     const bool haveUnsavedCfg = lastSavedCfg_ != getConfig();
@@ -3181,8 +3182,8 @@ bool MainDialog::loadConfiguration(const std::vector<Zstring>& filePaths)
     //add default exclusion filter: this is only ever relevant when creating new configurations!
     //a default XmlGuiConfig does not need these user-specific exclusions!
     Zstring& excludeFilter = newGuiCfg.mainCfg.globalFilter.excludeFilter;
-    if (!excludeFilter.empty() && !endsWith(excludeFilter, Zstr("\n")))
-        excludeFilter += Zstr("\n");
+    if (!excludeFilter.empty() && !endsWith(excludeFilter, Zstr('\n')))
+        excludeFilter += Zstr('\n');
     excludeFilter += globalCfg_.gui.defaultExclusionFilter;
 
     if (!filePaths.empty()) //empty cfg file list means "use default"
@@ -3886,7 +3887,7 @@ void MainDialog::OnCompare(wxCommandEvent& event)
     m_gridOverview->clearSelection(GridEventPolicy::ALLOW);
 
     //play (optional) sound notification
-    if (!globalCfg_.soundFileCompareFinished.empty() && fileAvailable(globalCfg_.soundFileCompareFinished))
+    if (!globalCfg_.soundFileCompareFinished.empty())
     {
         //wxWidgets shows modal error dialog by default => NO!
         wxLog* oldLogTarget = wxLog::SetActiveTarget(new wxLogStderr); //transfer and receive ownership!
@@ -4052,7 +4053,7 @@ void MainDialog::OnStartSync(wxCommandEvent& event)
     std::vector<std::wstring> jobNames;
     for (const Zstring& cfgFilePath : activeConfigFiles_)
         jobNames.push_back(equalNativePath(cfgFilePath, lastRunConfigPath_) ?
-                           L"[" + _("Last session") + L"]" :
+                           L'[' + _("Last session") + L']' :
                            extractJobName(cfgFilePath));
 
     using FinalRequest = StatusHandlerFloatingDialog::FinalRequest;
@@ -4112,7 +4113,7 @@ void MainDialog::OnStartSync(wxCommandEvent& event)
         catch (AbortProcess&) {}
 
         StatusHandlerFloatingDialog::Result r = statusHandler.reportResults(guiCfg.mainCfg.postSyncCommand, guiCfg.mainCfg.postSyncCondition,
-                                                                            guiCfg.mainCfg.altLogFolderPathPhrase, globalCfg_.logfilesMaxAgeDays, logFilePathsToKeep,
+                                                                            guiCfg.mainCfg.altLogFolderPathPhrase, globalCfg_.logfilesMaxAgeDays, globalCfg_.logFormat, logFilePathsToKeep,
                                                                             guiCfg.mainCfg.emailNotifyAddress, guiCfg.mainCfg.emailNotifyCondition); //noexcept
         //---------------------------------------------------------------------------
 
@@ -4320,7 +4321,7 @@ void MainDialog::updateConfigLastRunStats(time_t lastRunTime, SyncResult result,
 
 void MainDialog::setLastOperationLog(const ProcessSummary& summary, const std::shared_ptr<const zen::ErrorLog>& errorLog)
 {
-    const wxBitmap statusImage = [&]
+    const wxBitmap syncResultImage = [&]
     {
         switch (summary.resultStatus)
         {
@@ -4336,23 +4337,22 @@ void MainDialog::setLastOperationLog(const ProcessSummary& summary, const std::s
         return wxNullBitmap;
     }();
 
-    const wxImage statusOverlayImage = [&]
+    const wxImage logOverlayImage = [&]
     {
-        switch (summary.resultStatus)
+        //don't use "resultStatus": There may be errors after sync, e.g. failure to save log file/send email!
+        if (errorLog)
         {
-            case SyncResult::finishedSuccess:
-                break;
-            case SyncResult::finishedWarning:
-                return getResourceImage(L"msg_warning_sicon").ConvertToImage();
-            case SyncResult::finishedError:
-            case SyncResult::aborted:
+            const ErrorLog::Stats logCount = errorLog->getStats();
+            if (logCount.error + logCount.fatal > 0)
                 return getResourceImage(L"msg_error_sicon").ConvertToImage();
+            if (logCount.warning > 0)
+                return getResourceImage(L"msg_warning_sicon").ConvertToImage();
         }
         return wxNullImage;
     }();
 
-    m_bitmapLogStatus->SetBitmap(statusImage);
-    m_staticTextLogStatus->SetLabel(getResultsStatusLabel(summary.resultStatus));
+    m_bitmapSyncResult->SetBitmap(syncResultImage);
+    m_staticTextSyncResult->SetLabel(getSyncResultLabel(summary.resultStatus));
 
 
     m_staticTextItemsProcessed->SetLabel(formatNumber(summary.statsProcessed.items));
@@ -4383,7 +4383,7 @@ void MainDialog::setLastOperationLog(const ProcessSummary& summary, const std::s
     //m_panelItemStats->Layout(); //needed?
     //m_panelTimeStats->Layout(); //
 
-    setImage(*m_bpButtonShowLog, layOver(getResourceImage(L"log_file").ConvertToImage(), statusOverlayImage, wxALIGN_BOTTOM | wxALIGN_RIGHT));
+    setImage(*m_bpButtonShowLog, layOver(getResourceImage(L"log_file").ConvertToImage(), logOverlayImage, wxALIGN_BOTTOM | wxALIGN_RIGHT));
     m_bpButtonShowLog->Show(static_cast<bool>(errorLog));
 }
 
@@ -5425,7 +5425,7 @@ void MainDialog::OnMenuExportFileList(wxCommandEvent& event)
             //write file
             FileOutput fileOut(FileOutput::ACC_OVERWRITE, filePath, nullptr /*notifyUnbufferedIO*/); //throw FileError
 
-            fileOut.write(&*header.begin(), header.size()); //throw FileError, (X)
+            fileOut.write(&header[0], header.size()); //throw FileError, (X)
             //main grid: write rows one after the other instead of creating one big string: memory allocation might fail; think 1 million rows!
             /*
             performance test case "export 600.000 rows" to CSV:
diff --git a/FreeFileSync/Source/ui/main_dlg.h b/FreeFileSync/Source/ui/main_dlg.h
index a18a3223..ceef4712 100644
--- a/FreeFileSync/Source/ui/main_dlg.h
+++ b/FreeFileSync/Source/ui/main_dlg.h
@@ -18,10 +18,10 @@
 #include "sync_cfg.h"
 #include "log_panel.h"
 #include "folder_history_box.h"
-#include "../base/status_handler.h"
+#include "../config.h"
+#include "../status_handler.h"
 #include "../base/algorithm.h"
-#include "../base/return_codes.h"
-
+#include "../return_codes.h"
 
 namespace fff
 {
diff --git a/FreeFileSync/Source/ui/progress_indicator.cpp b/FreeFileSync/Source/ui/progress_indicator.cpp
index 8cb37ee5..04c20716 100644
--- a/FreeFileSync/Source/ui/progress_indicator.cpp
+++ b/FreeFileSync/Source/ui/progress_indicator.cpp
@@ -24,13 +24,13 @@
 #include <zen/perf.h>
 #include <wx+/choice_enum.h>
 #include "gui_generated.h"
-#include "../base/ffs_paths.h"
-#include "../base/perf_check.h"
-#include "../base/icon_buffer.h"
 #include "tray_icon.h"
 #include "taskbar.h"
 #include "log_panel.h"
 #include "app_icon.h"
+#include "../ffs_paths.h"
+#include "../perf_check.h"
+#include "../icon_buffer.h"
 
 
 using namespace zen;
@@ -998,9 +998,9 @@ template <class TopLevelDialog>
 void SyncProgressDialogImpl<TopLevelDialog>::setExternalStatus(const wxString& status, const wxString& progress) //progress may be empty!
 {
     //sys tray: order "top-down": jobname, status, progress
-    wxString systrayTooltip = jobName_.empty() ? status : jobName_ + L"\n" + status;
+    wxString systrayTooltip = jobName_.empty() ? status : jobName_ + L'\n' + status;
     if (!progress.empty())
-        systrayTooltip += L" " + progress;
+        systrayTooltip += L' ' + progress;
 
     //window caption/taskbar; inverse order: progress, status, jobname
     wxString title = progress.empty() ? status : progress + L" | " + status;
@@ -1009,7 +1009,7 @@ void SyncProgressDialogImpl<TopLevelDialog>::setExternalStatus(const wxString& s
         title += L" | " + jobName_;
 
     const TimeComp tc = getLocalTime(std::chrono::system_clock::to_time_t(syncStartTime_)); //returns empty string on failure
-    title += L" | " + formatTime<std::wstring>(FORMAT_DATE_TIME, tc);
+    title += L" | " + utfTo<std::wstring>(formatTime(formatDateTimeTag, tc));
     //---------------------------------------------------------------------------
 
     //systray tooltip, if window is minimized
@@ -1341,7 +1341,7 @@ void SyncProgressDialogImpl<TopLevelDialog>::showSummary(SyncResult resultStatus
     }();
     pnl_.m_bitmapStatus->SetBitmap(statusImage);
 
-    pnl_.m_staticTextPhase->SetLabel(getResultsStatusLabel(resultStatus));
+    pnl_.m_staticTextPhase->SetLabel(getSyncResultLabel(resultStatus));
     //pnl_.m_bitmapStatus->SetToolTip(); -> redundant
 
     //show status on Windows 7 taskbar
@@ -1360,7 +1360,7 @@ void SyncProgressDialogImpl<TopLevelDialog>::showSummary(SyncResult resultStatus
         }
     //----------------------------------
 
-    setExternalStatus(getResultsStatusLabel(resultStatus), wxString());
+    setExternalStatus(getSyncResultLabel(resultStatus), wxString());
 
     //this->EnableCloseButton(true);
 
@@ -1407,7 +1407,8 @@ void SyncProgressDialogImpl<TopLevelDialog>::showSummary(SyncResult resultStatus
     pnl_.m_notebookResult->AddPage(logPanel, _("Log"), false /*bSelect*/);
 
     //show log instead of graph if errors occurred! (not required for ignored warnings)
-    if (log.ref().getItemCount(MSG_TYPE_ERROR | MSG_TYPE_FATAL_ERROR) > 0)
+    const ErrorLog::Stats logCount = log.ref().getStats();
+    if (logCount.error + logCount.fatal > 0)
         pnl_.m_notebookResult->ChangeSelection(pagePosLog);
 
     //fill image list to cope with wxNotebook image setting design desaster...
@@ -1443,11 +1444,12 @@ void SyncProgressDialogImpl<TopLevelDialog>::showSummary(SyncResult resultStatus
     switch (resultStatus)
     {
         case SyncResult::aborted:
+            warn_static("we really should play sound if cancel on error is set, and only not play if user-aborted")
             break;
         case SyncResult::finishedError:
         case SyncResult::finishedWarning:
         case SyncResult::finishedSuccess:
-            if (!soundFileSyncComplete_.empty() && fileAvailable(soundFileSyncComplete_))
+            if (!soundFileSyncComplete_.empty())
             {
                 //wxWidgets shows modal error dialog by default => NO!
                 wxLog* oldLogTarget = wxLog::SetActiveTarget(new wxLogStderr); //transfer and receive ownership!
diff --git a/FreeFileSync/Source/ui/progress_indicator.h b/FreeFileSync/Source/ui/progress_indicator.h
index 5289f5e9..300078fa 100644
--- a/FreeFileSync/Source/ui/progress_indicator.h
+++ b/FreeFileSync/Source/ui/progress_indicator.h
@@ -11,9 +11,9 @@
 #include <zen/error_log.h>
 #include <zen/zstring.h>
 #include <wx/frame.h>
-#include "../base/config.h"
-#include "../base/status_handler.h"
-#include "../base/return_codes.h"
+#include "../config.h"
+#include "../status_handler.h"
+#include "../return_codes.h"
 
 
 namespace fff
diff --git a/FreeFileSync/Source/ui/small_dlgs.cpp b/FreeFileSync/Source/ui/small_dlgs.cpp
index d7bcebe9..39855f3c 100644
--- a/FreeFileSync/Source/ui/small_dlgs.cpp
+++ b/FreeFileSync/Source/ui/small_dlgs.cpp
@@ -31,19 +31,19 @@
 #include "folder_selector.h"
 #include "version_check.h"
 #include "abstract_folder_picker.h"
+#include "../afs/concrete.h"
+#include "../afs/gdrive.h"
+#include "../afs/ftp.h"
+#include "../afs/sftp.h"
 #include "../base/algorithm.h"
-#include "../base/ffs_paths.h"
 #include "../base/synchronization.h"
-#include "../base/help_provider.h"
 #include "../base/path_filter.h"
-#include "../base/status_handler.h" //uiUpdateDue()
-#include "../base/log_file.h"
-#include "../base/icon_buffer.h"
+#include "../status_handler.h" //uiUpdateDue()
 #include "../version/version.h"
-#include "../afs/concrete.h"
-#include "../afs/gdrive.h"
-#include "../afs/sftp.h"
-#include "../afs/ftp.h"
+#include "../log_file.h"
+#include "../ffs_paths.h"
+#include "../help_provider.h"
+#include "../icon_buffer.h"
 
 
 
@@ -98,7 +98,7 @@ AboutDlg::AboutDlg(wxWindow* parent) : AboutDlgGenerated(parent)
 #endif
 
     build += SPACED_BULLET;
-    build += formatTime<wxString>(FORMAT_DATE, getCompileTime());
+    build += utfTo<wxString>(formatTime(formatDateTag, getCompileTime()));
 
     m_staticTextVersion->SetLabel(replaceCpy(_("Version: %x"), L"%x", build));
 
@@ -275,7 +275,7 @@ CloudSetupDlg::CloudSetupDlg(wxWindow* parent, Zstring& folderPathPhrase, size_t
     m_staticTextConnectionsLabelSub->SetLabel(L"(" + _("Connections") + L")");
 
     //use spacer to keep dialog height stable, no matter if key file options are visible
-    bSizerAuthInner->Add(0, m_panelAuth->GetSize().GetHeight());
+    bSizerAuthInner->Add(0, m_panelAuth->GetSize().y);
 
     //---------------------------------------------------------
     wxArrayString googleUsers;
@@ -480,10 +480,11 @@ bool CloudSetupDlg::acceptFileDrop(const std::vector<Zstring>& shellItemPaths)
 {
     if (shellItemPaths.empty())
         return false;
+
     const Zstring ext = getFileExtension(shellItemPaths[0]);
     return ext.empty() ||
-           equalAsciiNoCase(ext, Zstr("pem")) ||
-           equalAsciiNoCase(ext, Zstr("ppk"));
+           equalAsciiNoCase(ext, "pem") ||
+           equalAsciiNoCase(ext, "ppk");
 }
 
 
@@ -1051,14 +1052,14 @@ public:
     OptionsDlg(wxWindow* parent, XmlGlobalSettings& globalCfg);
 
 private:
-    void OnOkay        (wxCommandEvent& event) override;
-    void OnResetDialogs(wxCommandEvent& event) override;
-    void OnDefault     (wxCommandEvent& event) override;
-    void OnCancel      (wxCommandEvent& event) override { EndModal(ReturnSmallDlg::BUTTON_CANCEL); }
-    void OnClose       (wxCloseEvent&   event) override { EndModal(ReturnSmallDlg::BUTTON_CANCEL); }
-    void OnAddRow      (wxCommandEvent& event) override;
-    void OnRemoveRow   (wxCommandEvent& event) override;
-    void OnHelpShowExamples(wxHyperlinkEvent& event) override { displayHelpEntry(L"external-applications", this); }
+    void OnOkay          (wxCommandEvent& event) override;
+    void OnRestoreDialogs(wxCommandEvent& event) override;
+    void OnDefault       (wxCommandEvent& event) override;
+    void OnCancel        (wxCommandEvent& event) override { EndModal(ReturnSmallDlg::BUTTON_CANCEL); }
+    void OnClose         (wxCloseEvent&   event) override { EndModal(ReturnSmallDlg::BUTTON_CANCEL); }
+    void OnAddRow        (wxCommandEvent& event) override;
+    void OnRemoveRow     (wxCommandEvent& event) override;
+    void OnHelpExternalApps(wxHyperlinkEvent& event) override { displayHelpEntry(L"external-applications", this); }
     void OnShowLogFolder   (wxHyperlinkEvent& event) override;
     void OnToggleLogfilesLimit(wxCommandEvent& event) override { updateGui(); }
 
@@ -1111,10 +1112,9 @@ OptionsDlg::OptionsDlg(wxWindow* parent, XmlGlobalSettings& globalSettings) :
     m_hyperlinkLogFolder->SetLabel(utfTo<wxString>(getDefaultLogFolderPath()));
     setRelativeFontSize(*m_hyperlinkLogFolder, 1.2);
 
-    m_staticTextResetDialogs->Wrap(std::max(fastFromDIP(250), m_buttonResetDialogs->GetMinSize().x));
-
     m_bitmapSettings          ->SetBitmap     (getResourceImage(L"settings"));
-    m_bitmapLogFile           ->SetBitmap(shrinkImage(getResourceImage(L"log_file").ConvertToImage(), fastFromDIP(20)));
+    m_bitmapWarnings          ->SetBitmap(shrinkImage(getResourceImage(L"msg_warning").ConvertToImage(), fastFromDIP(20)));
+    m_bitmapLogFile           ->SetBitmap(shrinkImage(getResourceImage(L"log_file"   ).ConvertToImage(), fastFromDIP(20)));
     m_bitmapNotificationSounds->SetBitmap     (getResourceImage(L"notification_sounds"));
     m_bitmapCompareDone       ->SetBitmap     (getResourceImage(L"compare_sicon"));
     m_bitmapSyncDone          ->SetBitmap     (getResourceImage(L"file_sync_sicon"));
@@ -1123,6 +1123,12 @@ OptionsDlg::OptionsDlg(wxWindow* parent, XmlGlobalSettings& globalSettings) :
     m_bpButtonAddRow          ->SetBitmapLabel(getResourceImage(L"item_add"));
     m_bpButtonRemoveRow       ->SetBitmapLabel(getResourceImage(L"item_remove"));
 
+    m_staticTextAllDialogsShown->SetLabel(L"(" + _("All dialogs shown") + L")");
+
+    m_staticTextResetDialogs->Wrap(std::max(fastFromDIP(250),
+                                            m_buttonRestoreDialogs     ->GetSize().x +
+                                            m_staticTextAllDialogsShown->GetSize().x));
+
     //--------------------------------------------------------------------------------
     m_checkBoxFailSafe       ->SetValue(globalSettings.failSafeFileCopy);
     m_checkBoxCopyLocked     ->SetValue(globalSettings.copyLockedFiles);
@@ -1131,19 +1137,29 @@ OptionsDlg::OptionsDlg(wxWindow* parent, XmlGlobalSettings& globalSettings) :
     m_checkBoxLogFilesMaxAge->SetValue(globalSettings.logfilesMaxAgeDays > 0);
     m_spinCtrlLogFilesMaxAge->SetValue(globalSettings.logfilesMaxAgeDays > 0 ? globalSettings.logfilesMaxAgeDays : XmlGlobalSettings().logfilesMaxAgeDays);
 
+    switch (globalSettings.logFormat)
+    {
+        case LogFileFormat::html:
+            m_radioBtnLogHtml->SetValue(true);
+            break;
+        case LogFileFormat::text:
+            m_radioBtnLogText->SetValue(true);
+            break;
+    }
+
     m_textCtrlSoundPathCompareDone->ChangeValue(utfTo<wxString>(globalSettings.soundFileCompareFinished));
     m_textCtrlSoundPathSyncDone   ->ChangeValue(utfTo<wxString>(globalSettings.soundFileSyncFinished));
-
-    setExtApp(globalSettings.gui.externalApps);
     //--------------------------------------------------------------------------------
 
-    updateGui();
-
     bSizerLockedFiles->Show(false);
     m_gridCustomCommand->SetMargins(0, 0);
 
     //temporarily set dummy value for window height calculations:
     setExtApp(std::vector<ExternalApp>(globalSettings.gui.externalApps.size() + 1));
+    confirmDlgs_             = defaultCfg_.confirmDlgs;             //
+    warnDlgs_                = defaultCfg_.warnDlgs;                //make sure m_staticTextAllDialogsShown is shown
+    autoCloseProgressDialog_ = defaultCfg_.autoCloseProgressDialog; //
+    updateGui();
 
     GetSizer()->SetSizeHints(this); //~=Fit() + SetMinSize()
     //=> works like a charm for GTK2 with window resizing problems and title bar corruption; e.g. Debian!!!
@@ -1151,6 +1167,10 @@ OptionsDlg::OptionsDlg(wxWindow* parent, XmlGlobalSettings& globalSettings) :
 
     //restore actual value:
     setExtApp(globalSettings.gui.externalApps);
+    confirmDlgs_             = globalSettings.confirmDlgs;
+    warnDlgs_                = globalSettings.warnDlgs;
+    autoCloseProgressDialog_ = globalSettings.autoCloseProgressDialog;
+    updateGui();
 
     //automatically fit column width to match total grid width
     Connect(wxEVT_SIZE, wxSizeEventHandler(OptionsDlg::onResize), nullptr, this);
@@ -1183,10 +1203,9 @@ void OptionsDlg::updateGui()
                                    warnDlgs_                != defaultCfg_.warnDlgs    ||
                                    autoCloseProgressDialog_ != defaultCfg_.autoCloseProgressDialog;
 
-    setBitmapTextLabel(*m_buttonResetDialogs, shrinkImage(getResourceImage(L"msg_warning").ConvertToImage(), fastFromDIP(20)),
-                       haveHiddenDialogs ? _("Show hidden dialogs again") : _("All dialogs shown"));
+    m_buttonRestoreDialogs->Enable(haveHiddenDialogs);
+    m_staticTextAllDialogsShown->Show(!haveHiddenDialogs);
     Layout();
-    m_buttonResetDialogs->Enable(haveHiddenDialogs);
 
     m_spinCtrlLogFilesMaxAge->Enable(m_checkBoxLogFilesMaxAge->GetValue());
 
@@ -1195,7 +1214,7 @@ void OptionsDlg::updateGui()
 }
 
 
-void OptionsDlg::OnResetDialogs(wxCommandEvent& event)
+void OptionsDlg::OnRestoreDialogs(wxCommandEvent& event)
 {
     confirmDlgs_             = defaultCfg_.confirmDlgs;
     warnDlgs_                = defaultCfg_.warnDlgs;
@@ -1248,6 +1267,16 @@ void OptionsDlg::OnDefault(wxCommandEvent& event)
     m_checkBoxLogFilesMaxAge->SetValue(defaultCfg_.logfilesMaxAgeDays > 0);
     m_spinCtrlLogFilesMaxAge->SetValue(defaultCfg_.logfilesMaxAgeDays > 0 ? defaultCfg_.logfilesMaxAgeDays : 14);
 
+    switch (defaultCfg_.logFormat)
+    {
+        case LogFileFormat::html:
+            m_radioBtnLogHtml->SetValue(true);
+            break;
+        case LogFileFormat::text:
+            m_radioBtnLogText->SetValue(true);
+            break;
+    }
+
     m_textCtrlSoundPathCompareDone->ChangeValue(utfTo<wxString>(defaultCfg_.soundFileCompareFinished));
     m_textCtrlSoundPathSyncDone   ->ChangeValue(utfTo<wxString>(defaultCfg_.soundFileSyncFinished));
 
@@ -1265,6 +1294,7 @@ void OptionsDlg::OnOkay(wxCommandEvent& event)
     globalCfgOut_.copyFilePermissions = m_checkBoxCopyPermissions->GetValue();
 
     globalCfgOut_.logfilesMaxAgeDays = m_checkBoxLogFilesMaxAge->GetValue() ? m_spinCtrlLogFilesMaxAge->GetValue() : -1;
+    globalCfgOut_.logFormat = m_radioBtnLogHtml->GetValue() ? LogFileFormat::html : LogFileFormat::text;
 
     globalCfgOut_.soundFileCompareFinished = utfTo<Zstring>(trimCpy(m_textCtrlSoundPathCompareDone->GetValue()));
     globalCfgOut_.soundFileSyncFinished    = utfTo<Zstring>(trimCpy(m_textCtrlSoundPathSyncDone   ->GetValue()));
@@ -1555,7 +1585,7 @@ ActivationDlg::ActivationDlg(wxWindow* parent,
 {
     setStandardButtonLayout(*bSizerStdButtons, StdButtons().setCancel(m_buttonCancel));
 
-    SetTitle(std::wstring(L"FreeFileSync ") + ffsVersion + L" [" + _("Donation Edition") + L"]");
+    SetTitle(std::wstring(L"FreeFileSync ") + ffsVersion + L" [" + _("Donation Edition") + L']');
 
     //setMainInstructionFont(*m_staticTextMain);
 
@@ -1636,7 +1666,7 @@ private:
     void updateGui()
     {
         const double fraction = bytesTotal_ == 0 ? 0 : 1.0 * bytesCurrent_ / bytesTotal_;
-        m_staticTextHeader->SetLabel(_("Downloading update...") + L" " +
+        m_staticTextHeader->SetLabel(_("Downloading update...") + L' ' +
                                      numberTo<std::wstring>(numeric::round(fraction * 100)) + L"% (" + formatFilesizeShort(bytesCurrent_) + L")");
         m_gaugeProgress->SetValue(numeric::round(fraction * GAUGE_FULL_RANGE));
 
diff --git a/FreeFileSync/Source/ui/small_dlgs.h b/FreeFileSync/Source/ui/small_dlgs.h
index ace76582..1849dc18 100644
--- a/FreeFileSync/Source/ui/small_dlgs.h
+++ b/FreeFileSync/Source/ui/small_dlgs.h
@@ -8,8 +8,8 @@
 #define SMALL_DLGS_H_8321790875018750245
 
 #include <wx/window.h>
-#include "../base/config.h"
 #include "../base/synchronization.h"
+#include "../config.h"
 
 
 namespace fff
diff --git a/FreeFileSync/Source/ui/sync_cfg.cpp b/FreeFileSync/Source/ui/sync_cfg.cpp
index 243fd315..318ec3b9 100644
--- a/FreeFileSync/Source/ui/sync_cfg.cpp
+++ b/FreeFileSync/Source/ui/sync_cfg.cpp
@@ -21,11 +21,12 @@
 #include "gui_generated.h"
 #include "command_box.h"
 #include "folder_selector.h"
-#include "../base/file_hierarchy.h"
-#include "../base/help_provider.h"
-#include "../base/log_file.h"
 #include "../base/norm_filter.h"
+#include "../base/file_hierarchy.h"
+#include "../help_provider.h"
+#include "../log_file.h"
 #include "../afs/concrete.h"
+#include "../base_tools.h"
 
 
 
@@ -99,7 +100,7 @@ private:
     std::map<AfsDevice, size_t> deviceParallelOps_;  //
 
     //------------- filter panel --------------------------
-    void OnHelpShowExamples(wxHyperlinkEvent& event) override { displayHelpEntry(L"exclude-items", this); }
+    void OnHelpFilterSettings(wxHyperlinkEvent& event) override { displayHelpEntry(L"exclude-items", this); }
     void OnChangeFilterOption(wxCommandEvent& event) override { updateFilterGui(); }
     void OnFilterReset       (wxCommandEvent& event) override { setFilterConfig(FilterConfig()); }
 
@@ -143,7 +144,13 @@ private:
     void OnDeletionRecycler   (wxCommandEvent& event) override { handleDeletion_ = DeletionPolicy::recycler;   updateSyncGui(); }
     void OnDeletionVersioning (wxCommandEvent& event) override { handleDeletion_ = DeletionPolicy::versioning; updateSyncGui(); }
 
-    void OnToggleMiscOption       (wxCommandEvent& event) override { updateMiscGui(); }
+    void OnToggleMiscOption(wxCommandEvent& event) override { updateMiscGui(); }
+    void OnToggleMiscEmail (wxCommandEvent& event) override
+    {
+        OnToggleMiscOption(event);
+        if (event.IsChecked())           //optimize UX
+            m_comboBoxEmail->SetFocus(); //
+    }
     void OnEmailAlways      (wxCommandEvent& event) override { emailNotifyCondition_ = ResultsNotification::always;       updateMiscGui(); }
     void OnEmailErrorWarning(wxCommandEvent& event) override { emailNotifyCondition_ = ResultsNotification::errorWarning; updateMiscGui(); }
     void OnEmailErrorOnly   (wxCommandEvent& event) override { emailNotifyCondition_ = ResultsNotification::errorOnly;    updateMiscGui(); }
@@ -283,7 +290,7 @@ emailHistoryOut_(emailHistory),
 commandHistoryOut_(commandHistory),
 globalPairCfg_(globalPairCfg),
 localPairCfg_(localPairConfig),
-enableExtraFeatures_(false),
+    enableExtraFeatures_(false),
 showMultipleCfgs_(showMultipleCfgs)
 {
     setStandardButtonLayout(*bSizerStdButtons, StdButtons().setAffirmative(m_buttonOkay).setCancel(m_buttonCancel));
@@ -393,8 +400,8 @@ showMultipleCfgs_(showMultipleCfgs)
 
     enumVersioningStyle_.
     add(VersioningStyle::replace,          _("Replace"),    _("Move files and replace if existing")).
-    add(VersioningStyle::timestampFolder, _("Time stamp") + L" [" + _("Folder") + L"]", _("Move files into a time-stamped subfolder")).
-    add(VersioningStyle::timestampFile,   _("Time stamp") + L" [" + _("File")   + L"]", _("Append a time stamp to each file name"));
+    add(VersioningStyle::timestampFolder, _("Time stamp") + L" [" + _("Folder") + L']', _("Move files into a time-stamped subfolder")).
+    add(VersioningStyle::timestampFile,   _("Time stamp") + L" [" + _("File")   + L']', _("Append a time stamp to each file name"));
 
     m_spinCtrlVersionMaxDays ->SetMinSize({fastFromDIP(60), -1}); //
     m_spinCtrlVersionCountMin->SetMinSize({fastFromDIP(60), -1}); //Hack: set size (why does wxWindow::Size() not work?)
@@ -407,7 +414,6 @@ showMultipleCfgs_(showMultipleCfgs)
     m_comboBoxEmail->SetHint(/*_("Example:") + */ L"john.doe@example.com");
     m_comboBoxEmail->setHistory(emailHistory, emailHistoryMax);
 
-    m_checkBoxSendEmail         ->Enable(enableExtraFeatures_);
     m_comboBoxEmail             ->Enable(enableExtraFeatures_);
     m_bpButtonEmailAlways       ->Enable(enableExtraFeatures_);
     m_bpButtonEmailErrorWarning ->Enable(enableExtraFeatures_);
@@ -455,7 +461,7 @@ showMultipleCfgs_(showMultipleCfgs)
     globalPairCfg_.syncCfg.versioningStyle  = VersioningStyle::timestampFile; //
     globalPairCfg_.syncCfg.versionMaxAgeDays = 30;                            //
     globalPairCfg_.miscCfg.altLogFolderPathPhrase = Zstr("dummy");            //
-    globalPairCfg_.miscCfg.emailNotifyAddress     = Zstr("dummy");            //
+    globalPairCfg_.miscCfg.emailNotifyAddress     =      "dummy";            //
 
     selectFolderPairConfig(-1);
 
@@ -1196,13 +1202,13 @@ MiscSyncConfig ConfigDialog::getMiscSyncOptions() const
     //----------------------------------------------------------------------------
     Zstring altLogPathPhrase = logfileDir_.getPath();
     if (altLogPathPhrase.empty())
-        altLogPathPhrase = Zstr(" "); //trigger error message on dialog close
+        altLogPathPhrase = Zstr(' '); //trigger error message on dialog close
     miscCfg.altLogFolderPathPhrase = m_checkBoxOverrideLogPath->GetValue() ? altLogPathPhrase : Zstring();
     //----------------------------------------------------------------------------
-    Zstring emailAddress = m_comboBoxEmail->getValue();
+    std::string emailAddress = utfTo<std::string>(m_comboBoxEmail->getValue());
     if (emailAddress.empty())
-        emailAddress = Zstr(" "); //trigger error message on dialog close
-    miscCfg.emailNotifyAddress = m_checkBoxSendEmail->GetValue() ? emailAddress : Zstring();
+        emailAddress = ' '; //trigger error message on dialog close
+    miscCfg.emailNotifyAddress = m_checkBoxSendEmail->GetValue() ? emailAddress : std::string();
     miscCfg.emailNotifyCondition = emailNotifyCondition_;
     //----------------------------------------------------------------------------
     return miscCfg;
@@ -1264,8 +1270,13 @@ void ConfigDialog::setMiscSyncOptions(const MiscSyncConfig& miscCfg)
     logfileDir_.setPath(m_checkBoxOverrideLogPath->GetValue() ? miscCfg.altLogFolderPathPhrase : getDefaultLogFolderPath());
     //can't use logfileDir_.setBackgroundText(): no text shown when control is disabled!
     //----------------------------------------------------------------------------
+    Zstring defaultEmail;
+    if (const std::vector<Zstring>& history = m_comboBoxEmail->getHistory();
+        !history.empty())
+        defaultEmail = history[0];
+
     m_checkBoxSendEmail->SetValue(!trimCpy(miscCfg.emailNotifyAddress).empty());
-    m_comboBoxEmail->setValue(miscCfg.emailNotifyAddress);
+    m_comboBoxEmail->setValue(m_checkBoxSendEmail->GetValue() ? utfTo<Zstring>(miscCfg.emailNotifyAddress) : defaultEmail);
     emailNotifyCondition_ = miscCfg.emailNotifyCondition;
     //----------------------------------------------------------------------------
     updateMiscGui();
@@ -1284,7 +1295,7 @@ void ConfigDialog::updateMiscGui()
     m_panelComparisonSettings->Layout(); //showing "retry count" can affect bSizerPerformance!
     //----------------------------------------------------------------------------
     const bool sendEmailEnabled = m_checkBoxSendEmail->GetValue();
-    m_bitmapEmail->SetBitmap(shrinkImage(greyScaleIfDisabled(getResourceImage(L"email"), sendEmailEnabled).ConvertToImage(), fastFromDIP(24)));
+    m_bitmapEmail->SetBitmap(greyScaleIfDisabled(getResourceImage(L"email"), sendEmailEnabled).ConvertToImage());
     m_comboBoxEmail->Show(sendEmailEnabled);
 
     auto updateButton = [successIcon = getResourceImage(L"msg_success_sicon").ConvertToImage(),
@@ -1334,7 +1345,9 @@ void ConfigDialog::updateMiscGui()
     m_bpButtonSelectAltLogFolder->Show(m_checkBoxOverrideLogPath->GetValue()); //
 
     m_panelSyncSettings->Layout(); //after showing/hiding m_buttonSelectLogFolder
-    m_panelLogfile->Refresh(); //removes a few artifacts when toggling email notifications
+
+    m_panelSyncSettings->Refresh(); //removes a few artifacts when toggling email notifications
+    m_panelLogfile     ->Refresh();//
 }
 
 
diff --git a/FreeFileSync/Source/ui/sync_cfg.h b/FreeFileSync/Source/ui/sync_cfg.h
index 568b1461..c9e481f7 100644
--- a/FreeFileSync/Source/ui/sync_cfg.h
+++ b/FreeFileSync/Source/ui/sync_cfg.h
@@ -41,7 +41,7 @@ struct MiscSyncConfig
 
     Zstring altLogFolderPathPhrase;
 
-    Zstring emailNotifyAddress;
+    std::string emailNotifyAddress;
     ResultsNotification emailNotifyCondition = ResultsNotification::always;
 };
 
diff --git a/FreeFileSync/Source/ui/tree_grid.cpp b/FreeFileSync/Source/ui/tree_grid.cpp
index 963ebdd0..e9a4ab62 100644
--- a/FreeFileSync/Source/ui/tree_grid.cpp
+++ b/FreeFileSync/Source/ui/tree_grid.cpp
@@ -17,7 +17,7 @@
 #include <wx+/context_menu.h>
 #include <wx+/image_resources.h>
 #include <wx+/image_tools.h>
-#include "../base/icon_buffer.h"
+#include "../icon_buffer.h"
 
 using namespace zen;
 using namespace fff;
@@ -736,7 +736,7 @@ private:
                             return dirRight;
                         else if (dirRight.empty())
                             return dirLeft;
-                        return dirLeft + L" " + EN_DASH + L"\n" + dirRight;
+                        return dirLeft + L' ' + EN_DASH + L'\n' + dirRight;
                     }
                 break;
 
@@ -1206,7 +1206,7 @@ TreeView& treegrid::getDataView(Grid& grid)
 {
     if (auto* prov = dynamic_cast<GridDataTree*>(grid.getDataProvider()))
         return prov->getDataView();
-    throw std::runtime_error(std::string(__FILE__) + "[" + numberTo<std::string>(__LINE__) + "] treegrid was not initialized.");
+    throw std::runtime_error(std::string(__FILE__) + '[' + numberTo<std::string>(__LINE__) + "] treegrid was not initialized.");
 }
 
 
diff --git a/FreeFileSync/Source/ui/version_check.cpp b/FreeFileSync/Source/ui/version_check.cpp
index 49a1c321..ac74401a 100644
--- a/FreeFileSync/Source/ui/version_check.cpp
+++ b/FreeFileSync/Source/ui/version_check.cpp
@@ -19,7 +19,7 @@
 #include <zen/thread.h>
 #include <wx+/popup_dlg.h>
 #include <wx+/image_resources.h>
-#include "../base/ffs_paths.h"
+#include "../ffs_paths.h"
 #include "../version/version.h"
 #include "small_dlgs.h"
 
@@ -167,7 +167,7 @@ void showUpdateAvailableDialog(wxWindow* parent, const std::string& onlineVersio
     switch (showConfirmationDialog(parent, DialogInfoType::info, PopupDialogCfg().
                                    setIcon(getResourceImage(L"update_available")).
                                    setTitle(_("Check for Program Updates")).
-                                   setMainInstructions(replaceCpy(_("FreeFileSync %x is available!"), L"%x", utfTo<std::wstring>(onlineVersion)) + L" " + _("Download now?")).
+                                   setMainInstructions(replaceCpy(_("FreeFileSync %x is available!"), L"%x", utfTo<std::wstring>(onlineVersion)) + L' ' + _("Download now?")).
                                    setDetailInstructions(updateDetailsMsg),
                                    _("&Download")))
     {
diff --git a/FreeFileSync/Source/version/version.h b/FreeFileSync/Source/version/version.h
index 933b9f4c..5496cd99 100644
--- a/FreeFileSync/Source/version/version.h
+++ b/FreeFileSync/Source/version/version.h
@@ -3,7 +3,7 @@
 
 namespace fff
 {
-const char ffsVersion[] = "10.20"; //internal linkage!
+const char ffsVersion[] = "10.21"; //internal linkage!
 const char FFS_VERSION_SEPARATOR = '.';
 }
 
diff --git a/libcurl/curl_wrap.h b/libcurl/curl_wrap.h
index dca056fc..40694e71 100644
--- a/libcurl/curl_wrap.h
+++ b/libcurl/curl_wrap.h
@@ -137,10 +137,11 @@ std::wstring formatCurlStatusCode(CURLcode sc)
             ZEN_CHECK_CASE_FOR_CONSTANT(CURLE_AUTH_ERROR);
             ZEN_CHECK_CASE_FOR_CONSTANT(CURLE_HTTP3);
             ZEN_CHECK_CASE_FOR_CONSTANT(CURL_LAST);
+            ZEN_CHECK_CASE_FOR_CONSTANT(CURLE_QUIC_CONNECT_ERROR);
     }
-    static_assert(CURL_LAST == CURLE_HTTP3 + 1);
+    static_assert(CURL_LAST == CURLE_QUIC_CONNECT_ERROR + 1);
 
-    return replaceCpy<std::wstring>(L"Curl status %x.", L"%x", numberTo<std::wstring>(static_cast<int>(sc)));
+    return replaceCpy<std::wstring>(L"Curl status %x", L"%x", numberTo<std::wstring>(static_cast<int>(sc)));
 }
 
 
diff --git a/libcurl/rest.cpp b/libcurl/rest.cpp
index 22583483..0d14dfc2 100644
--- a/libcurl/rest.cpp
+++ b/libcurl/rest.cpp
@@ -125,10 +125,10 @@ HttpSession::Result HttpSession::perform(const std::string& serverRelPath,
     }
 
     if (std::any_of(extraOptions.begin(), extraOptions.end(), [](const CurlOption& o) { return o.option == CURLOPT_WRITEFUNCTION || o.option == CURLOPT_READFUNCTION; }))
-    throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__)); //Option already used here!
+    throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__)); //Option already used here!
 
     if (readRequest && std::any_of(extraOptions.begin(), extraOptions.end(), [](const CurlOption& o) { return o.option == CURLOPT_POSTFIELDS; }))
-    throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__)); //Contradicting options: CURLOPT_READFUNCTION, CURLOPT_POSTFIELDS
+    throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__)); //Contradicting options: CURLOPT_READFUNCTION, CURLOPT_POSTFIELDS
 
     //---------------------------------------------------
     curl_slist* headers = nullptr; //"libcurl will not copy the entire list so you must keep it!"
@@ -160,15 +160,15 @@ HttpSession::Result HttpSession::perform(const std::string& serverRelPath,
         std::rethrow_exception(userCallbackException); //throw X
     //=======================================================================================================
 
-    long httpStatusCode = 0; //optional
-    /*const CURLcode rc = */ ::curl_easy_getinfo(easyHandle_, CURLINFO_RESPONSE_CODE, &httpStatusCode);
+    long httpStatus = 0; //optional
+    /*const CURLcode rc = */ ::curl_easy_getinfo(easyHandle_, CURLINFO_RESPONSE_CODE, &httpStatus);
 
     if (rcPerf != CURLE_OK)
     {
         std::wstring errorMsg = trimCpy(utfTo<std::wstring>(curlErrorBuf)); //optional
 
-        if (httpStatusCode != 0) //optional
-            errorMsg += (errorMsg.empty() ? L"" : L"\n") + formatHttpStatusCode(httpStatusCode);
+        if (httpStatus != 0) //optional
+            errorMsg += (errorMsg.empty() ? L"" : L"\n") + formatHttpStatus(httpStatus);
 #if 0
         //utfTo<std::wstring>(::curl_easy_strerror(ec)) is uninteresting
         //use CURLINFO_OS_ERRNO ?? https://curl.haxx.se/libcurl/c/CURLINFO_OS_ERRNO.html
@@ -181,5 +181,5 @@ HttpSession::Result HttpSession::perform(const std::string& serverRelPath,
     }
 
     lastSuccessfulUseTime_ = std::chrono::steady_clock::now();
-    return { static_cast<int>(httpStatusCode) /*, contentType ? contentType : ""*/ };
+    return { static_cast<int>(httpStatus) /*, contentType ? contentType : ""*/ };
 }
diff --git a/libssh2/libssh2_wrap.h b/libssh2/libssh2_wrap.h
index 37a62a24..98b73af2 100644
--- a/libssh2/libssh2_wrap.h
+++ b/libssh2/libssh2_wrap.h
@@ -174,8 +174,10 @@ std::wstring formatSshStatusCode(int sc)
             ZEN_CHECK_CASE_FOR_CONSTANT(LIBSSH2_ERROR_KNOWN_HOSTS);
             ZEN_CHECK_CASE_FOR_CONSTANT(LIBSSH2_ERROR_CHANNEL_WINDOW_FULL);
             ZEN_CHECK_CASE_FOR_CONSTANT(LIBSSH2_ERROR_KEYFILE_AUTH_FAILED);
+
+    default:
+            return replaceCpy<std::wstring>(L"SSH status %x", L"%x", numberTo<std::wstring>(sc));
     }
-    return replaceCpy<std::wstring>(L"SSH status %x.", L"%x", numberTo<std::wstring>(sc));
 }
 
 
@@ -219,7 +221,7 @@ std::wstring formatSftpStatusCode(unsigned long sc)
         case 30: return L"SSH_FX_GROUP_INVALID";
         case 31: return L"SSH_FX_NO_MATCHING_BYTE_RANGE_LOCK";
 
-		default: return replaceCpy<std::wstring>(L"SFTP status %x.", L"%x", numberTo<std::wstring>(sc));
+		default: return replaceCpy<std::wstring>(L"SFTP status %x", L"%x", numberTo<std::wstring>(sc));
 		//*INDENT-ON*
     }
 }
diff --git a/wx+/file_drop.cpp b/wx+/file_drop.cpp
index 65d5d861..938f9dbd 100644
--- a/wx+/file_drop.cpp
+++ b/wx+/file_drop.cpp
@@ -23,9 +23,23 @@ namespace
 class WindowDropTarget : public wxFileDropTarget
 {
 public:
-    WindowDropTarget(wxWindow& dropWindow) : dropWindow_(dropWindow) {}
+    WindowDropTarget(const wxWindow& dropWindow) : dropWindow_(dropWindow) {}
 
 private:
+    wxDragResult OnDragOver(wxCoord x, wxCoord y, wxDragResult def) override
+    {
+        //why the FUCK I is drag & drop still working while showing another modal dialog!???
+        //why the FUCK II is drag & drop working even when dropWindow is disabled!??              [Windows] => we can fix this
+        //why the FUCK III is dropWindow NOT disabled while showing another modal dialog!??? [macOS, Linux] => we CANNOT fix this: FUUUUUUUUUUUUUU...
+        if (!dropWindow_.IsEnabled())
+            return wxDragNone;
+
+        return wxFileDropTarget::OnDragOver(x, y, def);
+    }
+
+    //"bool wxDropTarget::GetData() [...] This method may only be called from within OnData()."
+    //=> FUUUUUUUUUUUUUU........ a.k.a. no support for DragDropValidator during mouse hover! >:(
+
     bool OnDropFiles(wxCoord x, wxCoord y, const wxArrayString& fileArray) override
     {
         /*Linux, MTP: we get an empty file array
@@ -35,6 +49,9 @@ private:
                 /run/user/1000/gvfs/mtp:host=%5Busb%3A001%2C002%5D/Telefonspeicher/Folder/file.txt
         */
 
+        if (!dropWindow_.IsEnabled())
+            return false;
+
         //wxPoint clientDropPos(x, y)
         std::vector<Zstring> filePaths;
         for (const wxString& file : fileArray)
@@ -46,12 +63,12 @@ private:
         return true;
     }
 
-    wxWindow& dropWindow_;
+    const wxWindow& dropWindow_;
 };
 }
 
 
-void zen::setupFileDrop(wxWindow& wnd)
+void zen::setupFileDrop(wxWindow& dropWindow)
 {
-    wnd.SetDropTarget(new WindowDropTarget(wnd)); /*takes ownership*/
+    dropWindow.SetDropTarget(new WindowDropTarget(dropWindow)); /*takes ownership*/
 }
diff --git a/wx+/file_drop.h b/wx+/file_drop.h
index 9826bf27..0a1089fc 100644
--- a/wx+/file_drop.h
+++ b/wx+/file_drop.h
@@ -58,8 +58,7 @@ using FileDropEventFunction = void (wxEvtHandler::*)(FileDropEvent&);
 
 
 
-
-void setupFileDrop(wxWindow& wnd);
+void setupFileDrop(wxWindow& dropWindow);
 }
 
 #endif //FILE_DROP_H_09457802957842560325626
diff --git a/wx+/grid.cpp b/wx+/grid.cpp
index fe168df6..c7b43d4a 100644
--- a/wx+/grid.cpp
+++ b/wx+/grid.cpp
@@ -159,7 +159,7 @@ wxSize GridData::drawCellText(wxDC& dc, const wxRect& rect, const std::wstring&
     */
 
     //truncate large texts and add ellipsis
-    assert(!contains(text, L"\n"));
+    assert(!contains(text, L'\n'));
 
     std::wstring textTrunc = text;
     wxSize extentTrunc = dc.GetTextExtent(textTrunc);
diff --git a/wx+/image_resources.cpp b/wx+/image_resources.cpp
index 070b9112..255a352e 100644
--- a/wx+/image_resources.cpp
+++ b/wx+/image_resources.cpp
@@ -231,7 +231,7 @@ void GlobalBitmaps::init(const Zstring& zipPath)
     {
         wxMemoryInputStream wxstream(stream.c_str(), stream.size()); //stream does not take ownership of data
         //bonus: work around wxWidgets bug: wxAnimation::Load() requires seekable input stream (zip-input stream is not seekable)
-          
+
         if (endsWith(fileName, L".png"))
         {
             wxImage img(wxstream, wxBITMAP_TYPE_PNG);
diff --git a/wx+/image_tools.cpp b/wx+/image_tools.cpp
index 8f94d1bc..9fcc5563 100644
--- a/wx+/image_tools.cpp
+++ b/wx+/image_tools.cpp
@@ -120,7 +120,7 @@ std::vector<std::pair<wxString, wxSize>> getTextExtentInfo(const wxString& text,
     dc.SetFont(font); //the font parameter of GetMultiLineTextExtent() is not evalated on OS X, wxWidgets 2.9.5, so apply it to the DC directly!
 
     std::vector<std::pair<wxString, wxSize>> lineInfo; //text + extent
-    for (const wxString& line : split(text, L"\n", SplitType::ALLOW_EMPTY))
+    for (const wxString& line : split(text, L'\n', SplitType::ALLOW_EMPTY))
         lineInfo.emplace_back(line, line.empty() ? wxSize() : dc.GetTextExtent(line));
 
     return lineInfo;
diff --git a/wx+/popup_dlg.cpp b/wx+/popup_dlg.cpp
index 11c4511f..c677cf57 100644
--- a/wx+/popup_dlg.cpp
+++ b/wx+/popup_dlg.cpp
@@ -45,7 +45,7 @@ void setBestInitialSize(wxTextCtrl& ctrl, const wxString& text, wxSize maxSize)
         auto itEnd = std::find(it, text.end(), L'\n');
         wxString line(it, itEnd);
         if (line.empty())
-            line = L" "; //GetTextExtent() returns (0, 0) for empty strings!
+            line = L' '; //GetTextExtent() returns (0, 0) for empty strings!
 
         wxSize sz = ctrl.GetTextExtent(line); //exactly gives row height, but does *not* consider newlines
         if (evalLineExtent(sz))
@@ -135,8 +135,8 @@ public:
         {
             wxString text;
             if (!cfg.textMain.empty())
-                text += L"\n";
-            text += trimCpy(cfg.textDetail) + L"\n"; //add empty top/bottom lines *instead* of using border space!
+                text += L'\n';
+            text += trimCpy(cfg.textDetail) + L'\n'; //add empty top/bottom lines *instead* of using border space!
             setBestInitialSize(*m_textCtrlTextDetail, text, wxSize(maxWidth, maxHeight));
             m_textCtrlTextDetail->ChangeValue(text);
         }
@@ -145,7 +145,7 @@ public:
 
         if (checkBoxValue_)
         {
-            assert(contains(cfg.checkBoxLabel, L"&"));
+            assert(contains(cfg.checkBoxLabel, L'&'));
             m_checkBoxCustom->SetLabel(cfg.checkBoxLabel);
             m_checkBoxCustom->SetValue(*checkBoxValue_);
         }
diff --git a/xBRZ/src/xbrz.cpp b/xBRZ/src/xbrz.cpp
index 5228073f..e2c25810 100644
--- a/xBRZ/src/xbrz.cpp
+++ b/xBRZ/src/xbrz.cpp
@@ -241,8 +241,8 @@ enum BlendType
 struct BlendResult
 {
     BlendType
-    /**/blend_f, blend_g,
-    /**/blend_j, blend_k;
+    blend_e, blend_f,
+             blend_h, blend_i;
 };
 
 
@@ -254,62 +254,57 @@ struct Kernel_3x3
     g, h, i;
 };
 
-struct Kernel_4x4 //kernel for preprocessing step
+struct Kernel_4x4 : Kernel_3x3
 {
-    uint32_t
-    a, b, c, //
-    e, f, g, // support reinterpret_cast from Kernel_4x4 => Kernel_3x3
-    i, j, k, //
-    m, n, o,
-    d, h, l, p;
+    uint32_t j, k, l, m, n, o, p;
 };
+/* input kernel for preprocessing step:
+
+    -----------------
+    | A | B | C | P |
+    |---|---|---|---|
+    | D | E | F | O |   evaluate the four corners between E, F, H, I
+    |---|---|---|---|   input pixel is at position E
+    | G | H | I | N |
+    |---|---|---|---|
+    | J | K | L | M |
+    -----------------                                                         */
 
-/* input kernel area naming convention:
------------------
-| A | B | C | D |
-|---|---|---|---|
-| E | F | G | H |   evaluate the four corners between F, G, J, K
-|---|---|---|---|   input pixel is at position F
-| I | J | K | L |
-|---|---|---|---|
-| M | N | O | P |
------------------
-*/
 template <class ColorDistance>
 FORCE_INLINE //detect blend direction
-BlendResult preProcessCorners(const Kernel_4x4& ker, const xbrz::ScalerCfg& cfg) //result: F, G, J, K corners of "GradientType"
+BlendResult preProcessCorners(const Kernel_4x4& ker, const xbrz::ScalerCfg& cfg) //result: E, F, H, I corners of "GradientType"
 {
 
     BlendResult result = {};
 
-    if ((ker.f == ker.g &&
-         ker.j == ker.k) ||
-        (ker.f == ker.j &&
-         ker.g == ker.k))
+    if ((ker.e == ker.f &&
+         ker.h == ker.i) ||
+        (ker.e == ker.h &&
+         ker.f == ker.i))
         return result;
 
     auto dist = [&](uint32_t pix1, uint32_t pix2) { return ColorDistance::dist(pix1, pix2, cfg.luminanceWeight); };
 
-    double jg = dist(ker.i, ker.f) + dist(ker.f, ker.c) + dist(ker.n, ker.k) + dist(ker.k, ker.h) + cfg.centerDirectionBias * dist(ker.j, ker.g);
-    double fk = dist(ker.e, ker.j) + dist(ker.j, ker.o) + dist(ker.b, ker.g) + dist(ker.g, ker.l) + cfg.centerDirectionBias * dist(ker.f, ker.k);
+    const double hf = dist(ker.g, ker.e) + dist(ker.e, ker.c) + dist(ker.k, ker.i) + dist(ker.i, ker.o) + cfg.centerDirectionBias * dist(ker.h, ker.f);
+    const double ei = dist(ker.d, ker.h) + dist(ker.h, ker.l) + dist(ker.b, ker.f) + dist(ker.f, ker.n) + cfg.centerDirectionBias * dist(ker.e, ker.i);
 
-    if (jg < fk) //test sample: 70% of values max(jg, fk) / min(jg, fk) are between 1.1 and 3.7 with median being 1.8
+    if (hf < ei) //test sample: 70% of values max(hf, ei) / min(hf, ei) are between 1.1 and 3.7 with median being 1.8
     {
-        const bool dominantGradient = cfg.dominantDirectionThreshold * jg < fk;
-        if (ker.f != ker.g && ker.f != ker.j)
-            result.blend_f = dominantGradient ? BLEND_DOMINANT : BLEND_NORMAL;
+        const bool dominantGradient = cfg.dominantDirectionThreshold * hf < ei;
+        if (ker.e != ker.f && ker.e != ker.h)
+            result.blend_e = dominantGradient ? BLEND_DOMINANT : BLEND_NORMAL;
 
-        if (ker.k != ker.j && ker.k != ker.g)
-            result.blend_k = dominantGradient ? BLEND_DOMINANT : BLEND_NORMAL;
+        if (ker.i != ker.h && ker.i != ker.f)
+            result.blend_i = dominantGradient ? BLEND_DOMINANT : BLEND_NORMAL;
     }
-    else if (fk < jg)
+    else if (ei < hf)
     {
-        const bool dominantGradient = cfg.dominantDirectionThreshold * fk < jg;
-        if (ker.j != ker.f && ker.j != ker.k)
-            result.blend_j = dominantGradient ? BLEND_DOMINANT : BLEND_NORMAL;
+        const bool dominantGradient = cfg.dominantDirectionThreshold * ei < hf;
+        if (ker.h != ker.e && ker.h != ker.i)
+            result.blend_h = dominantGradient ? BLEND_DOMINANT : BLEND_NORMAL;
 
-        if (ker.g != ker.f && ker.g != ker.k)
-            result.blend_g = dominantGradient ? BLEND_DOMINANT : BLEND_NORMAL;
+        if (ker.f != ker.e && ker.f != ker.i)
+            result.blend_f = dominantGradient ? BLEND_DOMINANT : BLEND_NORMAL;
     }
     return result;
 }
@@ -371,13 +366,13 @@ template <> inline unsigned char rotateBlendInfo<ROT_270>(unsigned char b) { ret
 | D | E | F | input pixel is at position E
 |---|---|---|
 | G | H | I |
--------------
-*/
+-------------                                  */
+
 template <class Scaler, class ColorDistance, RotationDegree rotDeg>
 FORCE_INLINE //perf: quite worth it!
 void blendPixel(const Kernel_3x3& ker,
                 uint32_t* target, int trgWidth,
-                unsigned char blendInfo, //result of preprocessing all four corners of pixel "e"
+                unsigned char blendInfo, //result of preprocessing all four corners of pixel "E"
                 const xbrz::ScalerCfg& cfg)
 {
     //#define a get_a<rotDeg>(ker)
@@ -469,21 +464,21 @@ public:
         s_p2(0 <= y + 2 && y + 2 < srcHeight ? src + srcWidth * (y + 2) : nullptr),
         srcWidth_(srcWidth) {}
 
-    void readDhlp(Kernel_4x4& ker, int x) const //(x, y) is at kernel position F
+    void readPonm(Kernel_4x4& ker, int x) const //(x, y) is at kernel position E
     {
         [[likely]] if (const int x_p2 = x + 2; 0 <= x_p2 && x_p2 < srcWidth_)
         {
-            ker.d = s_m1 ? s_m1[x_p2] : 0;
-            ker.h = s_0  ? s_0 [x_p2] : 0;
-            ker.l = s_p1 ? s_p1[x_p2] : 0;
-            ker.p = s_p2 ? s_p2[x_p2] : 0;
+            ker.p = s_m1 ? s_m1[x_p2] : 0;
+            ker.o = s_0  ? s_0 [x_p2] : 0;
+            ker.n = s_p1 ? s_p1[x_p2] : 0;
+            ker.m = s_p2 ? s_p2[x_p2] : 0;
         }
         else
         {
-            ker.d = 0;
-            ker.h = 0;
-            ker.l = 0;
             ker.p = 0;
+            ker.o = 0;
+            ker.n = 0;
+            ker.m = 0;
         }
     }
 
@@ -506,13 +501,13 @@ public:
         s_p2(src + srcWidth * std::clamp(y + 2, 0, srcHeight - 1)),
         srcWidth_(srcWidth) {}
 
-    void readDhlp(Kernel_4x4& ker, int x) const //(x, y) is at kernel position F
+    void readPonm(Kernel_4x4& ker, int x) const //(x, y) is at kernel position E
     {
         const int x_p2 = std::clamp(x + 2, 0, srcWidth_ - 1);
-        ker.d = s_m1[x_p2];
-        ker.h = s_0 [x_p2];
-        ker.l = s_p1[x_p2];
-        ker.p = s_p2[x_p2];
+        ker.p = s_m1[x_p2];
+        ker.o = s_0 [x_p2];
+        ker.n = s_p1[x_p2];
+        ker.m = s_p2[x_p2];
     }
 
 private:
@@ -545,61 +540,61 @@ void scaleImage(const uint32_t* src, uint32_t* trg, int srcWidth, int srcHeight,
 
         //initialize at position x = -1
         Kernel_4x4 ker4 = {};
-        oobReader.readDhlp(ker4, -4); //hack: read a, e, i, m at x = -1
-        ker4.a = ker4.d;
-        ker4.e = ker4.h;
-        ker4.i = ker4.l;
-        ker4.m = ker4.p;
-
-        oobReader.readDhlp(ker4, -3);
-        ker4.b = ker4.d;
-        ker4.f = ker4.h;
-        ker4.j = ker4.l;
-        ker4.n = ker4.p;
-
-        oobReader.readDhlp(ker4, -2);
-        ker4.c = ker4.d;
-        ker4.g = ker4.h;
-        ker4.k = ker4.l;
-        ker4.o = ker4.p;
-
-        oobReader.readDhlp(ker4, -1);
+        oobReader.readPonm(ker4, -4); //hack: read a, d, g, j at x = -1
+        ker4.a = ker4.p;
+        ker4.d = ker4.o;
+        ker4.g = ker4.n;
+        ker4.j = ker4.m;
+
+        oobReader.readPonm(ker4, -3);
+        ker4.b = ker4.p;
+        ker4.e = ker4.o;
+        ker4.h = ker4.n;
+        ker4.k = ker4.m;
+
+        oobReader.readPonm(ker4, -2);
+        ker4.c = ker4.p;
+        ker4.f = ker4.o;
+        ker4.i = ker4.n;
+        ker4.l = ker4.m;
+
+        oobReader.readPonm(ker4, -1);
 
         {
             const BlendResult res = preProcessCorners<ColorDistance>(ker4, cfg);
-            clearAddTopL(preProcBuf[0], res.blend_k); //set 1st known corner for (0, yFirst)
+            clearAddTopL(preProcBuf[0], res.blend_i); //set 1st known corner for (0, yFirst)
         }
 
         for (int x = 0; x < srcWidth; ++x)
         {
             ker4.a = ker4.b;    //shift previous kernel to the left
-            ker4.e = ker4.f;    // -----------------
-            ker4.i = ker4.j;    // | A | B | C | D |
-            ker4.m = ker4.n;    // |---|---|---|---|
-            /**/                // | E | F | G | H | (x, yFirst - 1) is at position F
-            ker4.b = ker4.c;    // |---|---|---|---|
-            ker4.f = ker4.g;    // | I | J | K | L |
+            ker4.d = ker4.e;    // -----------------
+            ker4.g = ker4.h;    // | A | B | C | P |
             ker4.j = ker4.k;    // |---|---|---|---|
-            ker4.n = ker4.o;    // | M | N | O | P |
+            /**/                // | D | E | F | O | (x, yFirst - 1) is at position E
+            ker4.b = ker4.c;    // |---|---|---|---|
+            ker4.e = ker4.f;    // | G | H | I | N |
+            ker4.h = ker4.i;    // |---|---|---|---|
+            ker4.k = ker4.l;    // | J | K | L | M |
             /**/                // -----------------
-            ker4.c = ker4.d;
-            ker4.g = ker4.h;
-            ker4.k = ker4.l;
-            ker4.o = ker4.p;
+            ker4.c = ker4.p;
+            ker4.f = ker4.o;
+            ker4.i = ker4.n;
+            ker4.l = ker4.m;
 
-            oobReader.readDhlp(ker4, x);
+            oobReader.readPonm(ker4, x);
 
             /*  preprocessing blend result:
                 ---------
-                | F | G |   evaluate corner between F, G, J, K
-                |---+---|   current input pixel is at position F
-                | J | K |
+                | E | F |   evaluate corner between E, F, H, I
+                |---+---|   current input pixel is at position E
+                | H | I |
                 ---------                                        */
             const BlendResult res = preProcessCorners<ColorDistance>(ker4, cfg);
-            addTopR(preProcBuf[x], res.blend_j); //set 2nd known corner for (x, yFirst)
+            addTopR(preProcBuf[x], res.blend_h); //set 2nd known corner for (x, yFirst)
 
             if (x + 1 < srcWidth)
-                clearAddTopL(preProcBuf[x + 1], res.blend_k); //set 1st known corner for (x + 1, yFirst)
+                clearAddTopL(preProcBuf[x + 1], res.blend_i); //set 1st known corner for (x + 1, yFirst)
         }
     }
     //------------------------------------------------------------------------------------
@@ -612,85 +607,85 @@ void scaleImage(const uint32_t* src, uint32_t* trg, int srcWidth, int srcHeight,
 
         //initialize at position x = -1
         Kernel_4x4 ker4 = {};
-        oobReader.readDhlp(ker4, -4); //hack: read a, e, i, m at x = -1
-        ker4.a = ker4.d;
-        ker4.e = ker4.h;
-        ker4.i = ker4.l;
-        ker4.m = ker4.p;
-
-        oobReader.readDhlp(ker4, -3);
-        ker4.b = ker4.d;
-        ker4.f = ker4.h;
-        ker4.j = ker4.l;
-        ker4.n = ker4.p;
-
-        oobReader.readDhlp(ker4, -2);
-        ker4.c = ker4.d;
-        ker4.g = ker4.h;
-        ker4.k = ker4.l;
-        ker4.o = ker4.p;
-
-        oobReader.readDhlp(ker4, -1);
+        oobReader.readPonm(ker4, -4); //hack: read a, d, g, j at x = -1
+        ker4.a = ker4.p;
+        ker4.d = ker4.o;
+        ker4.g = ker4.n;
+        ker4.j = ker4.m;
+
+        oobReader.readPonm(ker4, -3);
+        ker4.b = ker4.p;
+        ker4.e = ker4.o;
+        ker4.h = ker4.n;
+        ker4.k = ker4.m;
+
+        oobReader.readPonm(ker4, -2);
+        ker4.c = ker4.p;
+        ker4.f = ker4.o;
+        ker4.i = ker4.n;
+        ker4.l = ker4.m;
+
+        oobReader.readPonm(ker4, -1);
 
         unsigned char blend_xy1 = 0; //corner blending for current (x, y + 1) position
         {
             const BlendResult res = preProcessCorners<ColorDistance>(ker4, cfg);
-            clearAddTopL(blend_xy1, res.blend_k); //set 1st known corner for (0, y + 1) and buffer for use on next column
+            clearAddTopL(blend_xy1, res.blend_i); //set 1st known corner for (0, y + 1) and buffer for use on next column
 
-            addBottomL(preProcBuf[0], res.blend_g); //set 3rd known corner for (0, y)
+            addBottomL(preProcBuf[0], res.blend_f); //set 3rd known corner for (0, y)
         }
 
         for (int x = 0; x < srcWidth; ++x, out += Scaler::scale)
         {
             ker4.a = ker4.b;    //shift previous kernel to the left
-            ker4.e = ker4.f;    // -----------------
-            ker4.i = ker4.j;    // | A | B | C | D |
-            ker4.m = ker4.n;    // |---|---|---|---|
-            /**/                // | E | F | G | H | (x, y) is at position F
-            ker4.b = ker4.c;    // |---|---|---|---|
-            ker4.f = ker4.g;    // | I | J | K | L |
+            ker4.d = ker4.e;    // -----------------
+            ker4.g = ker4.h;    // | A | B | C | P |
             ker4.j = ker4.k;    // |---|---|---|---|
-            ker4.n = ker4.o;    // | M | N | O | P |
+            /**/                // | D | E | F | O | (x, y) is at position E
+            ker4.b = ker4.c;    // |---|---|---|---|
+            ker4.e = ker4.f;    // | G | H | I | N |
+            ker4.h = ker4.i;    // |---|---|---|---|
+            ker4.k = ker4.l;    // | J | K | L | M |
             /**/                // -----------------
-            ker4.c = ker4.d;
-            ker4.g = ker4.h;
-            ker4.k = ker4.l;
-            ker4.o = ker4.p;
+            ker4.c = ker4.p;
+            ker4.f = ker4.o;
+            ker4.i = ker4.n;
+            ker4.l = ker4.m;
 
-            oobReader.readDhlp(ker4, x);
+            oobReader.readPonm(ker4, x);
 
             //evaluate the four corners on bottom-right of current pixel
             unsigned char blend_xy = preProcBuf[x]; //for current (x, y) position
             {
                 /*  preprocessing blend result:
                     ---------
-                    | F | G |   evaluate corner between F, G, J, K
-                    |---+---|   current input pixel is at position F
-                    | J | K |
+                    | E | F |   evaluate corner between E, F, H, I
+                    |---+---|   current input pixel is at position E
+                    | H | I |
                     ---------                                        */
                 const BlendResult res = preProcessCorners<ColorDistance>(ker4, cfg);
-                addBottomR(blend_xy, res.blend_f); //all four corners of (x, y) have been determined at this point due to processing sequence!
+                addBottomR(blend_xy, res.blend_e); //all four corners of (x, y) have been determined at this point due to processing sequence!
 
-                addTopR(blend_xy1, res.blend_j); //set 2nd known corner for (x, y + 1)
+                addTopR(blend_xy1, res.blend_h); //set 2nd known corner for (x, y + 1)
                 preProcBuf[x] = blend_xy1; //store on current buffer position for use on next row
 
                 [[likely]] if (x + 1 < srcWidth)
                 {
                     //blend_xy1 -> blend_x1y1
-                    clearAddTopL(blend_xy1, res.blend_k); //set 1st known corner for (x + 1, y + 1) and buffer for use on next column
+                    clearAddTopL(blend_xy1, res.blend_i); //set 1st known corner for (x + 1, y + 1) and buffer for use on next column
 
-                    addBottomL(preProcBuf[x + 1], res.blend_g); //set 3rd known corner for (x + 1, y)
+                    addBottomL(preProcBuf[x + 1], res.blend_f); //set 3rd known corner for (x + 1, y)
                 }
             }
 
             //fill block of size scale * scale with the given color
-            fillBlock(out, trgWidth * sizeof(uint32_t), ker4.f, Scaler::scale, Scaler::scale);
+            fillBlock(out, trgWidth * sizeof(uint32_t), ker4.e, Scaler::scale, Scaler::scale);
             //place *after* preprocessing step, to not overwrite the results while processing the last pixel!
 
             //blend all four corners of current pixel
             if (blendingNeeded(blend_xy))
             {
-                const auto& ker3 = reinterpret_cast<const Kernel_3x3&>(ker4); //"The Things We Do for Perf"
+                const Kernel_3x3& ker3 = ker4; //"The Things We Do for Perf"
                 blendPixel<Scaler, ColorDistance, ROT_0  >(ker3, out, trgWidth, blend_xy, cfg);
                 blendPixel<Scaler, ColorDistance, ROT_90 >(ker3, out, trgWidth, blend_xy, cfg);
                 blendPixel<Scaler, ColorDistance, ROT_180>(ker3, out, trgWidth, blend_xy, cfg);
@@ -800,8 +795,8 @@ struct Scaler3x : public ColorGradient
     {
         //model a round corner
         alphaGrad<45, 100>(out.template ref<2, 2>(), col); //exact: 0.4545939598
-        //alphaGrad<7, 256>(out.template ref<2, 1>(), col); //0.02826017254 -> negligible + avoid conflicts with other rotations for this odd scale
-        //alphaGrad<7, 256>(out.template ref<1, 2>(), col); //0.02826017254
+        //alphaGrad<3, 100>(out.template ref<2, 1>(), col); //0.02826017254 -> negligible + avoid overlap with other rotations at this scale
+        //alphaGrad<3, 100>(out.template ref<1, 2>(), col); //0.02826017254
     }
 };
 
@@ -957,8 +952,8 @@ struct Scaler5x : public ColorGradient
         alphaGrad<86, 100>(out.template ref<4, 4>(), col); //exact: 0.8631434088
         alphaGrad<23, 100>(out.template ref<4, 3>(), col); //0.2306749731
         alphaGrad<23, 100>(out.template ref<3, 4>(), col); //0.2306749731
-        //alphaGrad<1, 64>(out.template ref<4, 2>(), col); //0.01676812367 -> negligible + avoid conflicts with other rotations for this odd scale
-        //alphaGrad<1, 64>(out.template ref<2, 4>(), col); //0.01676812367
+        //alphaGrad<2, 100>(out.template ref<4, 2>(), col); //0.01676812367 -> negligible + avoid overlap with other rotations at this scale
+        //alphaGrad<2, 100>(out.template ref<2, 4>(), col); //0.01676812367
     }
 };
 
diff --git a/zen/basic_math.h b/zen/basic_math.h
index 8a32ee69..26dda9a6 100644
--- a/zen/basic_math.h
+++ b/zen/basic_math.h
@@ -14,6 +14,7 @@
 #include <functional>
 #include <cassert>
 #include "type_traits.h"
+#include "legacy_compiler.h"
 
 
 namespace numeric
@@ -53,17 +54,6 @@ double mad(RandomAccessIterator first, RandomAccessIterator last); //note: inval
 template <class InputIterator>
 double norm2(InputIterator first, InputIterator last);
 
-//constants
-const double pi    = 3.14159265358979323846;
-const double e     = 2.71828182845904523536;
-const double sqrt2 = 1.41421356237309504880;
-const double ln2   = 0.693147180559945309417;
-
-#if __cpp_lib_math_constants //C++20
-    #error implement math constants from <numbers> header
-#endif
-//static_assert(pi + e + sqrt2 + ln2 == 7.9672352249818781, "whoopsie");
-
 //----------------------------------------------------------------------------------
 
 
@@ -213,14 +203,14 @@ T power(T value)
 inline
 double radToDeg(double rad)
 {
-    return rad * 180.0 / numeric::pi;
+    return rad * (180.0 / std::numbers::pi);
 }
 
 
 inline
 double degToRad(double degree)
 {
-    return degree * numeric::pi / 180.0;
+    return degree / (180.0 / std::numbers::pi);
 }
 
 
diff --git a/zen/crc.h b/zen/crc.h
index df460a03..0570cced 100644
--- a/zen/crc.h
+++ b/zen/crc.h
@@ -64,38 +64,32 @@ uint32_t getCrc32(ByteIterator first, ByteIterator last) //https://en.wikipedia.
 {
     constexpr uint32_t crcTable[] =
     {
-        0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
-        0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
-        0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
-        0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
-        0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
-        0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
-        0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
-        0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
-        0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
-        0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
-        0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
-        0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
-        0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
-        0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
-        0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
-        0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
-        0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
-        0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
-        0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
-        0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
-        0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
-        0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
-        0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
-        0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
-        0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
-        0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
-        0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
-        0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
-        0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
-        0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
-        0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
-        0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
+        0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
+        0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
+        0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
+        0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
+        0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
+        0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
+        0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
+        0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
+        0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
+        0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
+        0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
+        0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
+        0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
+        0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
+        0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
+        0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
+        0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
+        0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
+        0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
+        0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
+        0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
+        0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
+        0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
+        0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
+        0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
+        0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
     };
     static_assert(arraySize(crcTable) == 256 && arrayAccumulate<uint64_t>(crcTable) == 549755813760);
     static_assert(sizeof(typename std::iterator_traits<ByteIterator>::value_type) == 1);
diff --git a/zen/dir_watcher.cpp b/zen/dir_watcher.cpp
index 94632ea4..307b48e5 100644
--- a/zen/dir_watcher.cpp
+++ b/zen/dir_watcher.cpp
@@ -85,7 +85,8 @@ DirWatcher::DirWatcher(const Zstring& dirPath) : //throw FileError
             const ErrorCode ec = getLastError(); //copy before directly/indirectly making other system calls!
             if (ec == ENOSPC) //fix misleading system message "No space left on device"
                 throw FileError(replaceCpy(_("Cannot monitor directory %x."), L"%x", fmtPath(subDirPath)),
-                                formatSystemError(L"inotify_add_watch", numberTo<std::wstring>(ec), L"The user limit on the total number of inotify watches was reached or the kernel failed to allocate a needed resource."));
+                                formatSystemError(L"inotify_add_watch", L"ENOSPC",
+                                                  L"The user limit on the total number of inotify watches was reached or the kernel failed to allocate a needed resource."));
 
             throw FileError(replaceCpy(_("Cannot monitor directory %x."), L"%x", fmtPath(subDirPath)), formatSystemError(L"inotify_add_watch", ec));
         }
diff --git a/zen/error_log.h b/zen/error_log.h
index cc52fc6e..ab23e33a 100644
--- a/zen/error_log.h
+++ b/zen/error_log.h
@@ -8,9 +8,7 @@
 #define ERROR_LOG_H_8917590832147915
 
 #include <cassert>
-#include <algorithm>
 #include <vector>
-//#include <string>
 #include "time.h"
 #include "i18n.h"
 #include "utf.h"
@@ -31,10 +29,10 @@ struct LogEntry
 {
     time_t      time = 0;
     MessageType type = MSG_TYPE_FATAL_ERROR;
-    Zstringw    message; //std::wstring may employ small string optimization: we cannot accept bloating the "ErrorLog::entries_" memory block below (think 1 million items)
+    Zstringc message; //conserve memory (=> avoid std::string SSO overhead!)
 };
 
-std::wstring formatMessage(const LogEntry& entry);
+std::string formatMessage(const LogEntry& entry);
 
 
 class ErrorLog
@@ -42,7 +40,14 @@ class ErrorLog
 public:
     void logMsg(const std::wstring& msg, MessageType type);
 
-    int getItemCount(int typeFilter = MSG_TYPE_INFO | MSG_TYPE_WARNING | MSG_TYPE_ERROR | MSG_TYPE_FATAL_ERROR) const;
+    struct Stats
+    {
+        int info    = 0;
+        int warning = 0;
+        int error   = 0;
+        int fatal   = 0;
+    };
+    Stats getStats() const;
 
     //subset of std::vector<> interface:
     using const_iterator = std::vector<LogEntry>::const_iterator;
@@ -65,59 +70,79 @@ private:
 inline
 void ErrorLog::logMsg(const std::wstring& msg, MessageType type)
 {
-    entries_.push_back({ std::time(nullptr), type, copyStringTo<Zstringw>(msg) });
+    entries_.push_back({ std::time(nullptr), type, utfTo<Zstringc>(msg) });
 }
 
 
-inline
-int ErrorLog::getItemCount(int typeFilter) const
-{
-    return static_cast<int>(std::count_if(entries_.begin(), entries_.end(), [typeFilter](const LogEntry& e) { return e.type & typeFilter; }));
-}
 
-
-inline 
-std::wstring getMessageTypeLabel(MessageType type)
+inline
+ErrorLog::Stats ErrorLog::getStats() const
 {
-        switch (type)
+    Stats count;
+    for (const LogEntry& entry : entries_)
+        switch (entry.type)
         {
             case MSG_TYPE_INFO:
-                return _("Info");
+                ++count.info;
+                break;
             case MSG_TYPE_WARNING:
-                return _("Warning");
+                ++count.warning;
+                break;
             case MSG_TYPE_ERROR:
-                return _("Error");
+                ++count.error;
+                break;
             case MSG_TYPE_FATAL_ERROR:
-                return _("Serious Error");
+                ++count.fatal;
+                break;
         }
-        assert(false);
-        return std::wstring();
+    assert(static_cast<int>(entries_.size()) == count.info + count.warning + count.error + count.fatal);
+    return count;
+}
+
+
+inline
+std::wstring getMessageTypeLabel(MessageType type)
+{
+    switch (type)
+    {
+        case MSG_TYPE_INFO:
+            return _("Info");
+        case MSG_TYPE_WARNING:
+            return _("Warning");
+        case MSG_TYPE_ERROR:
+            return _("Error");
+        case MSG_TYPE_FATAL_ERROR:
+            return _("Serious Error");
+    }
+    assert(false);
+    return std::wstring();
 }
 
 
 inline
-std::wstring formatMessage(const LogEntry& entry)
+std::string formatMessage(const LogEntry& entry)
 {
-    std::wstring msgFmt = L"[" + formatTime<std::wstring>(FORMAT_TIME, getLocalTime(entry.time)) + L"]  " + getMessageTypeLabel(entry.type) + L":  ";
+    std::string msgFmt = '[' + utfTo<std::string>(formatTime(formatTimeTag, getLocalTime(entry.time))) + "]  " + utfTo<std::string>(getMessageTypeLabel(entry.type)) + ":  ";
     const size_t prefixLen = unicodeLength(msgFmt); //consider Unicode!
 
-    const Zstringw msg = trimCpy(entry.message);
-    static_assert(std::is_same_v<decltype(msg), const Zstringw>, "don't worry about copying as long as we're using a ref-counted string!");
+    const Zstringc msg = trimCpy(entry.message);
+    static_assert(std::is_same_v<decltype(msg), const Zstringc>, "don't worry about copying as long as we're using a ref-counted string!");
 
     for (auto it = msg.begin(); it != msg.end(); )
-        if (*it == L'\n')
+        if (*it == '\n')
         {
-            msgFmt += L'\n';
-            msgFmt.append(prefixLen, L' ');
+            msgFmt += '\n';
+            msgFmt.append(prefixLen, ' ');
             ++it;
             //skip duplicate newlines
-            for (;it != msg.end() && *it == L'\n'; ++it)
+            for (; it != msg.end() && *it == '\n'; ++it)
                 ;
         }
         else
             msgFmt += *it++;
 
-    return msgFmt += L'\n';
+    msgFmt += '\n';
+    return msgFmt;
 }
 }
 
diff --git a/zen/file_access.cpp b/zen/file_access.cpp
index e23d48be..4f6704d2 100644
--- a/zen/file_access.cpp
+++ b/zen/file_access.cpp
@@ -311,7 +311,7 @@ void moveAndRenameFileSub(const Zstring& pathFrom, const Zstring& pathTo, bool r
 {
     auto throwException = [&](int ec)
     {
-        const std::wstring errorMsg = replaceCpy(replaceCpy(_("Cannot move file %x to %y."), L"%x", L"\n" + fmtPath(pathFrom)), L"%y", L"\n" + fmtPath(pathTo));
+        const std::wstring errorMsg = replaceCpy(replaceCpy(_("Cannot move file %x to %y."), L"%x", L'\n' + fmtPath(pathFrom)), L"%y", L'\n' + fmtPath(pathTo));
         const std::wstring errorDescr = formatSystemError(L"rename", ec);
 
         if (ec == EXDEV)
@@ -575,7 +575,7 @@ void zen::copySymlink(const Zstring& sourcePath, const Zstring& targetPath, bool
     const Zstring linkPath = getSymlinkTargetRaw(sourcePath); //throw FileError; accept broken symlinks
 
     if (::symlink(linkPath.c_str(), targetPath.c_str()) != 0)
-        THROW_LAST_FILE_ERROR(replaceCpy(replaceCpy(_("Cannot copy symbolic link %x to %y."), L"%x", L"\n" + fmtPath(sourcePath)), L"%y", L"\n" + fmtPath(targetPath)), L"symlink");
+        THROW_LAST_FILE_ERROR(replaceCpy(replaceCpy(_("Cannot copy symbolic link %x to %y."), L"%x", L'\n' + fmtPath(sourcePath)), L"%y", L'\n' + fmtPath(targetPath)), L"symlink");
 
     //allow only consistent objects to be created -> don't place before ::symlink(); targetPath may already exist!
     ZEN_ON_SCOPE_FAIL(try { removeSymlinkPlain(targetPath); /*throw FileError*/ }
diff --git a/zen/file_io.cpp b/zen/file_io.cpp
index e788bcfe..b78259e0 100644
--- a/zen/file_io.cpp
+++ b/zen/file_io.cpp
@@ -68,7 +68,7 @@ FileBase::FileHandle openHandleForRead(const Zstring& filePath) //throw FileErro
                 return name + printNumber<std::wstring>(L"0%06o", m & S_IFMT);
             }();
             throw FileError(replaceCpy(_("Cannot open file %x."), L"%x", fmtPath(filePath)),
-                            _("Unsupported item type.") + L" [" + typeName + L"]");
+                            _("Unsupported item type.") + L" [" + typeName + L']');
         }
     }
     //else: let ::open() fail for errors like "not existing"
@@ -100,7 +100,7 @@ FileInput::FileInput(const Zstring& filePath, const IOCallback& notifyUnbuffered
 size_t FileInput::tryRead(void* buffer, size_t bytesToRead) //throw FileError, ErrorFileLocked; may return short, only 0 means EOF!
 {
     if (bytesToRead == 0) //"read() with a count of 0 returns zero" => indistinguishable from end of file! => check!
-        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
     assert(bytesToRead == getBlockSize());
 
     ssize_t bytesRead = 0;
@@ -215,7 +215,7 @@ FileOutput::~FileOutput()
 size_t FileOutput::tryWrite(const void* buffer, size_t bytesToWrite) //throw FileError; may return short! CONTRACT: bytesToWrite > 0
 {
     if (bytesToWrite == 0)
-        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
     assert(bytesToWrite <= getBlockSize());
 
     ssize_t bytesWritten = 0;
diff --git a/zen/file_io.h b/zen/file_io.h
index 54bde5aa..b47c6077 100644
--- a/zen/file_io.h
+++ b/zen/file_io.h
@@ -119,7 +119,7 @@ void saveBinContainer(const Zstring& filePath, const BinContainer& buffer, const
     if (!buffer.empty())
     {
         /*snake oil?*/ fileOut.preAllocateSpaceBestEffort(buffer.size()); //throw FileError
-        fileOut.write(&*buffer.begin(), buffer.size()); //throw FileError, X
+        fileOut.write(&buffer[0], buffer.size()); //throw FileError, X
     }
     fileOut.finalize();                                 //throw FileError, X
 }
diff --git a/zen/format_unit.cpp b/zen/format_unit.cpp
index f2df4153..91a881dc 100644
--- a/zen/format_unit.cpp
+++ b/zen/format_unit.cpp
@@ -11,6 +11,7 @@
 #include "i18n.h"
 #include "time.h"
 #include "globals.h"
+#include "utf.h"
 
     #include <clocale> //thousands separator
     #include "utf.h"   //
@@ -115,7 +116,7 @@ std::wstring roundToBlock(double timeInHigh,
 
     std::wstring output = formatUnitTime(roundedtimeInLow / unitLowPerHigh, unitHigh);
     if (unitLowPerHigh > blockSizeLow)
-        output += L" " + formatUnitTime(roundedtimeInLow % unitLowPerHigh, unitLow);
+        output += L' ' + formatUnitTime(roundedtimeInLow % unitLowPerHigh, unitLow);
     return output;
 }
 }
@@ -194,7 +195,7 @@ std::wstring zen::formatUtcToLocalTime(time_t utcTime)
 
     TimeComp loc = getLocalTime(utcTime);
 
-    std::wstring dateString = formatTime<std::wstring>(L"%x  %X", loc);
+    std::wstring dateString = utfTo<std::wstring>(formatTime(Zstr("%x  %X"), loc));
     return !dateString.empty() ? dateString : errorMsg();
 }
 
diff --git a/zen/guid.h b/zen/guid.h
index 657ed07a..88059be8 100644
--- a/zen/guid.h
+++ b/zen/guid.h
@@ -26,8 +26,8 @@ std::string generateGUID() //creates a 16-byte GUID
 
 #if __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 25) //getentropy() requires glibc 2.25 (ldd --version) PS: CentOS 7 is on 2.17
     if (::getentropy(&guid[0], guid.size()) != 0)  //"The maximum permitted value for the length argument is 256"
-        throw std::runtime_error(std::string(__FILE__) + "[" + numberTo<std::string>(__LINE__) + "] Failed to generate GUID." +
-                                 "\n" + utfTo<std::string>(formatSystemError(L"getentropy", errno)));
+        throw std::runtime_error(std::string(__FILE__) + '[' + numberTo<std::string>(__LINE__) + "] Failed to generate GUID." + "\n\n" +
+                                 utfTo<std::string>(formatSystemError(L"getentropy", errno)));
 #else
     class RandomGeneratorPosix
     {
@@ -35,8 +35,8 @@ std::string generateGUID() //creates a 16-byte GUID
         RandomGeneratorPosix()
         {
             if (fd_ == -1)
-                throw std::runtime_error(std::string(__FILE__) + "[" + numberTo<std::string>(__LINE__) + "] Failed to generate GUID." +
-                                         "\n" + utfTo<std::string>(formatSystemError(L"open", errno)));
+                throw std::runtime_error(std::string(__FILE__) + '[' + numberTo<std::string>(__LINE__) + "] Failed to generate GUID." + "\n\n" +
+                                         utfTo<std::string>(formatSystemError(L"open", errno)));
         }
 
         ~RandomGeneratorPosix() { ::close(fd_); }
@@ -47,8 +47,8 @@ std::string generateGUID() //creates a 16-byte GUID
             {
                 const ssize_t bytesRead = ::read(fd_, static_cast<char*>(buf) + offset, size - offset);
                 if (bytesRead < 1) //0 means EOF => error in this context (should check for buffer overflow, too?)
-                    throw std::runtime_error(std::string(__FILE__) + "[" + numberTo<std::string>(__LINE__) + "] Failed to generate GUID." +
-                                             "\n" + utfTo<std::string>(formatSystemError(L"read", bytesRead < 0 ? errno : EIO)));
+                    throw std::runtime_error(std::string(__FILE__) + '[' + numberTo<std::string>(__LINE__) + "] Failed to generate GUID." + "\n\n" +
+                                             utfTo<std::string>(formatSystemError(L"read", bytesRead < 0 ? errno : EIO)));
                 offset += bytesRead;
                 assert(offset <= size);
             }
diff --git a/zen/http.cpp b/zen/http.cpp
index 8cd99d7a..c6a390de 100644
--- a/zen/http.cpp
+++ b/zen/http.cpp
@@ -19,7 +19,7 @@ class HttpInputStream::Impl
 public:
     Impl(const Zstring& url,
          const std::string* postBuf /*issue POST if bound, GET otherwise*/,
-         const Zstring& contentType, //required for POST
+         const std::string& contentType, //required for POST
          bool disableGetCache /*not relevant for POST (= never cached)*/,
          const Zstring& userAgent,
          const Zstring* caCertFilePath /*optional: enable certificate validation*/,
@@ -37,9 +37,9 @@ public:
 
         const bool useTls = [&]
         {
-            if (startsWithAsciiNoCase(url, Zstr("http://")))
+            if (startsWithAsciiNoCase(url, "http://"))
                 return false;
-            if (startsWithAsciiNoCase(url, Zstr("https://")))
+            if (startsWithAsciiNoCase(url, "https://"))
                 return true;
             throw SysError(L"URL uses unexpected protocol.");
         }();
@@ -49,7 +49,7 @@ public:
         std::map<std::string, std::string, LessAsciiNoCase> headers;
 
         if (postBuf && !contentType.empty())
-            headers["Content-Type"] = utfTo<std::string>(contentType);
+            headers["Content-Type"] = contentType;
 
         if (useTls) //HTTP default port: 443, see %WINDIR%\system32\drivers\etc\services
         {
@@ -96,7 +96,7 @@ public:
             const size_t blockSize = std::min(static_cast<size_t>(1024), memBuf_.size()); //smaller block size: try to only read header part
             buf.resize(buf.size() + blockSize);
             const size_t bytesReceived = tryRead(&*(buf.end() - blockSize), blockSize); //throw SysError
-            buf.resize(buf.size() - blockSize + bytesReceived); //caveat: unsigned arithmetics
+            buf.resize(buf.size() - (blockSize - bytesReceived)); //caveat: unsigned arithmetics
 
             if (contains(buf, headerDelim))
             {
@@ -122,8 +122,8 @@ public:
         statusCode_ = stringTo<int>(statusItems[1]);
 
         for (const std::string& line : split(headersBuf, "\r\n", SplitType::SKIP_EMPTY))
-            responseHeaders_[trimCpy(beforeFirst(line, ":", IF_MISSING_RETURN_ALL))] =
-                /**/         trimCpy(afterFirst (line, ":", IF_MISSING_RETURN_NONE));
+            responseHeaders_[trimCpy(beforeFirst(line, ':', IF_MISSING_RETURN_ALL))] =
+                /**/         trimCpy(afterFirst (line, ':', IF_MISSING_RETURN_NONE));
 
         //try to get "Content-Length" header if available
         if (const std::string* value = getHeader("Content-Length"))
@@ -236,7 +236,7 @@ namespace
 {
 std::unique_ptr<HttpInputStream::Impl> sendHttpRequestImpl(const Zstring& url,
                                                            const std::string* postBuf /*issue POST if bound, GET otherwise*/,
-                                                           const Zstring& contentType, //required for POST
+                                                           const std::string& contentType, //required for POST
                                                            const Zstring& userAgent,
                                                            const Zstring* caCertFilePath /*optional: enable certificate validation*/,
                                                            const IOCallback& notifyUnbufferedIO) //throw SysError, X
@@ -248,8 +248,8 @@ std::unique_ptr<HttpInputStream::Impl> sendHttpRequestImpl(const Zstring& url,
         auto response = std::make_unique<HttpInputStream::Impl>(urlRed, postBuf, contentType, false /*disableGetCache*/, userAgent, caCertFilePath, notifyUnbufferedIO); //throw SysError, X
 
         //https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#3xx_Redirection
-        const int httpStatusCode = response->getStatusCode();
-        if (httpStatusCode / 100 == 3) //e.g. 301, 302, 303, 307... we're not too greedy since we check location, too!
+        const int httpStatus = response->getStatusCode();
+        if (httpStatus / 100 == 3) //e.g. 301, 302, 303, 307... we're not too greedy since we check location, too!
         {
             const std::string* value = response->getHeader("Location");
             if (!value || value->empty())
@@ -259,8 +259,8 @@ std::unique_ptr<HttpInputStream::Impl> sendHttpRequestImpl(const Zstring& url,
         }
         else
         {
-            if (httpStatusCode != 200) //HTTP_STATUS_OK(200)
-                throw SysError(formatHttpStatusCode(httpStatusCode)); //e.g. HTTP_STATUS_NOT_FOUND(404)
+            if (httpStatus != 200) //HTTP_STATUS_OK(200)
+                throw SysError(formatHttpStatus(httpStatus)); //e.g. HTTP_STATUS_NOT_FOUND(404)
 
             return response;
         }
@@ -340,19 +340,19 @@ std::vector<std::pair<std::string, std::string>> zen::xWwwFormUrlDecode(const st
 
 HttpInputStream zen::sendHttpGet(const Zstring& url, const Zstring& userAgent, const Zstring* caCertFilePath, const IOCallback& notifyUnbufferedIO) //throw SysError, X
 {
-    return sendHttpRequestImpl(url, nullptr /*postBuf*/, Zstr("") /*contentType*/, userAgent, caCertFilePath, notifyUnbufferedIO); //throw SysError, X, X
+    return sendHttpRequestImpl(url, nullptr /*postBuf*/, "" /*contentType*/, userAgent, caCertFilePath, notifyUnbufferedIO); //throw SysError, X, X
 }
 
 
 HttpInputStream zen::sendHttpPost(const Zstring& url, const std::vector<std::pair<std::string, std::string>>& postParams,
                                   const Zstring& userAgent, const Zstring* caCertFilePath, const IOCallback& notifyUnbufferedIO) //throw SysError, X
 {
-    return sendHttpPost(url, xWwwFormUrlEncode(postParams), Zstr("application/x-www-form-urlencoded"), userAgent, caCertFilePath, notifyUnbufferedIO); //throw SysError, X
+    return sendHttpPost(url, xWwwFormUrlEncode(postParams), "application/x-www-form-urlencoded", userAgent, caCertFilePath, notifyUnbufferedIO); //throw SysError, X
 }
 
 
 
-HttpInputStream zen::sendHttpPost(const Zstring& url, const std::string& postBuf, const Zstring& contentType,
+HttpInputStream zen::sendHttpPost(const Zstring& url, const std::string& postBuf, const std::string& contentType,
                                   const Zstring& userAgent, const Zstring* caCertFilePath, const IOCallback& notifyUnbufferedIO) //throw SysError, X
 {
     return sendHttpRequestImpl(url, &postBuf, contentType, userAgent, caCertFilePath, notifyUnbufferedIO); //throw SysError, X
@@ -365,7 +365,7 @@ bool zen::internetIsAlive() //noexcept
     {
         auto response = std::make_unique<HttpInputStream::Impl>(Zstr("http://www.google.com/"),
                                                                 nullptr /*postParams*/,
-                                                                Zstr("") /*contentType*/,
+                                                                "" /*contentType*/,
                                                                 true /*disableGetCache*/,
                                                                 Zstr("FreeFileSync"),
                                                                 nullptr /*caCertFilePath*/,
@@ -380,7 +380,7 @@ bool zen::internetIsAlive() //noexcept
 }
 
 
-std::wstring zen::formatHttpStatusCode(int sc)
+std::wstring zen::formatHttpStatus(int sc)
 {
     const wchar_t* statusText = [&] //https://en.wikipedia.org/wiki/List_of_HTTP_status_codes
     {
@@ -462,13 +462,13 @@ std::wstring zen::formatHttpStatusCode(int sc)
 }
 
 
-bool zen::isValidEmail(const Zstring& email)
+bool zen::isValidEmail(const std::string& email)
 {
     //https://en.wikipedia.org/wiki/Email_address#Syntax
     //https://tools.ietf.org/html/rfc3696 => note errata! https://www.rfc-editor.org/errata_search.php?rfc=3696
     //https://tools.ietf.org/html/rfc5321
-    std::string local  = utfTo<std::string>(beforeLast(email, Zstr('@'), IF_MISSING_RETURN_NONE));
-    std::string domain = utfTo<std::string>( afterLast(email, Zstr('@'), IF_MISSING_RETURN_NONE));
+    std::string local  = beforeLast(email, '@', IF_MISSING_RETURN_NONE);
+    std::string domain =  afterLast(email, '@', IF_MISSING_RETURN_NONE);
     //consider: "t@st"@email.com t\@st@email.com"
 
     auto stripComments = [](std::string& part)
@@ -517,7 +517,7 @@ bool zen::isValidEmail(const Zstring& email)
 }
 
 
-std::string zen::htmlSpecialChars(const std::string& str)
+std::string zen::htmlSpecialChars(const std::string_view& str)
 {
     //mirror PHP: https://github.com/php/php-src/blob/e99d5d39239c611e1e7304e79e88545c4e71a073/ext/standard/html_tables.h#L6189
     std::string output;
diff --git a/zen/http.h b/zen/http.h
index fbaa09de..09395f8f 100644
--- a/zen/http.h
+++ b/zen/http.h
@@ -48,15 +48,15 @@ HttpInputStream sendHttpPost(const Zstring& url,
                              const IOCallback& notifyUnbufferedIO /*throw X*/); //throw SysError, X
 
 HttpInputStream sendHttpPost(const Zstring& url,
-                             const std::string& postBuf, const Zstring& contentType,
+                             const std::string& postBuf, const std::string& contentType,
                              const Zstring& userAgent,
                              const Zstring* caCertFilePath /*optional: enable certificate validation*/,
                              const IOCallback& notifyUnbufferedIO /*throw X*/); //throw SysError, X
 
 bool internetIsAlive(); //noexcept
-std::wstring formatHttpStatusCode(int httpStatusCode);
-bool isValidEmail(const Zstring& email);
-std::string htmlSpecialChars(const std::string& str);
+std::wstring formatHttpStatus(int httpStatus);
+bool isValidEmail(const std::string& email);
+std::string htmlSpecialChars(const std::string_view& str);
 
 std::string xWwwFormUrlEncode(const std::vector<std::pair<std::string, std::string>>& paramPairs);
 std::vector<std::pair<std::string, std::string>> xWwwFormUrlDecode(const std::string& str);
diff --git a/zen/legacy_compiler.h b/zen/legacy_compiler.h
index 54dd7f59..8d44f3f7 100644
--- a/zen/legacy_compiler.h
+++ b/zen/legacy_compiler.h
@@ -8,11 +8,6 @@
 #define LEGACY_COMPILER_H_839567308565656789
 
 
-#if !__cpp_lib_erase_if
-    #include <vector>
-    #include <set>
-    #include <map>
-#endif
 
 
 //https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations
@@ -58,8 +53,18 @@ private:
     T* const data_;
 };
 
-//---------------------------------------------------------------------------------
 
+#if __cpp_lib_math_constants
+    #error get rid of workaround:
+#endif
+
+namespace numbers
+{
+const double pi    = 3.14159265358979323846;
+const double e     = 2.71828182845904523536;
+const double sqrt2 = 1.41421356237309504880;
+const double ln2   = 0.693147180559945309417;
+}
 }
 
 
diff --git a/zen/open_ssl.cpp b/zen/open_ssl.cpp
index dc9c8a19..b823f8ca 100644
--- a/zen/open_ssl.cpp
+++ b/zen/open_ssl.cpp
@@ -322,8 +322,8 @@ std::string createSignature(const std::string& message, EVP_PKEY* privateKey) //
                               reinterpret_cast<unsigned char*>(&signature[0]), //unsigned char* sigret,
                               &sigLen) != 1)                                   //size_t* siglen
         throw SysError(formatLastOpenSSLError(L"EVP_DigestSignFinal"));
-    signature.resize(sigLen);
 
+    signature.resize(sigLen);
     return signature;
 }
 
@@ -373,7 +373,7 @@ void zen::verifySignature(const std::string& message, const std::string& signatu
 
 namespace
 {
-std::wstring formatSslErrorRaw(int ec)
+std::wstring formatSslErrorCode(int ec)
 {
     switch (ec)
     {
@@ -388,12 +388,15 @@ std::wstring formatSslErrorRaw(int ec)
             ZEN_CHECK_CASE_FOR_CONSTANT(SSL_ERROR_WANT_ACCEPT);
             ZEN_CHECK_CASE_FOR_CONSTANT(SSL_ERROR_WANT_ASYNC);
             ZEN_CHECK_CASE_FOR_CONSTANT(SSL_ERROR_WANT_ASYNC_JOB);
+            ZEN_CHECK_CASE_FOR_CONSTANT(SSL_ERROR_WANT_CLIENT_HELLO_CB);
+
+        default:
+            return replaceCpy<std::wstring>(L"SSL error %x", L"%x", numberTo<std::wstring>(ec));
     }
-    return L"Unknown SSL error: " + numberTo<std::wstring>(ec);
 }
 
 
-std::wstring formatX509ErrorRaw(long ec)
+std::wstring formatX509ErrorCode(long ec)
 {
     switch (ec)
     {
@@ -473,8 +476,10 @@ std::wstring formatX509ErrorRaw(long ec)
             ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_OCSP_VERIFY_NEEDED);
             ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_OCSP_VERIFY_FAILED);
             ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_OCSP_CERT_UNKNOWN);
+
+        default:
+            return replaceCpy<std::wstring>(L"X509 error %x", L"%x", numberTo<std::wstring>(ec));
     }
-    return L"Unknown X509 error: " + numberTo<std::wstring>(ec);
 }
 }
 
@@ -487,7 +492,7 @@ public:
     {
         ZEN_ON_SCOPE_FAIL(cleanup(); /*destructor call would lead to member double clean-up!!!*/);
 
-        ctx_ = ::SSL_CTX_new(TLS_client_method());
+        ctx_ = ::SSL_CTX_new(::TLS_client_method());
         if (!ctx_)
             throw SysError(formatLastOpenSSLError(L"SSL_CTX_new"));
 
@@ -526,13 +531,13 @@ public:
 
         const int rv = ::SSL_connect(ssl_); //implicitly calls SSL_set_connect_state()
         if (rv != 1)
-            throw SysError(formatLastOpenSSLError(L"SSL_connect") + L" " + formatSslErrorRaw(::SSL_get_error(ssl_, rv)));
+            throw SysError(formatLastOpenSSLError(L"SSL_connect") + L' ' + formatSslErrorCode(::SSL_get_error(ssl_, rv)));
 
         if (caCertFilePath)
         {
             const long verifyResult = ::SSL_get_verify_result(ssl_);
             if (verifyResult != X509_V_OK)
-                throw SysError(formatSystemError(L"SSL_get_verify_result", formatX509ErrorRaw(verifyResult), L""));
+                throw SysError(formatSystemError(L"SSL_get_verify_result", formatX509ErrorCode(verifyResult), L""));
         }
     }
 
@@ -554,7 +559,7 @@ public:
     size_t tryRead(void* buffer, size_t bytesToRead) //throw SysError; may return short, only 0 means EOF!
     {
         if (bytesToRead == 0) //"read() with a count of 0 returns zero" => indistinguishable from end of file! => check!
-            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
 
         size_t bytesReceived = 0;
         const int rv = ::SSL_read_ex(ssl_, buffer, bytesToRead, &bytesReceived);
@@ -564,7 +569,7 @@ public:
             if (sslError == SSL_ERROR_ZERO_RETURN || //EOF + close_notify alert
                 (sslError == SSL_ERROR_SYSCALL && ::ERR_peek_last_error() == 0)) //EOF: only expected for HTTP/1.0
                 return 0;
-            throw SysError(formatLastOpenSSLError(L"SSL_read_ex") + L" " + formatSslErrorRaw(sslError));
+            throw SysError(formatLastOpenSSLError(L"SSL_read_ex") + L' ' + formatSslErrorCode(sslError));
         }
         assert(bytesReceived > 0); //SSL_read_ex() considers EOF an error!
         if (bytesReceived > bytesToRead) //better safe than sorry
@@ -576,12 +581,12 @@ public:
     size_t tryWrite(const void* buffer, size_t bytesToWrite) //throw SysError; may return short! CONTRACT: bytesToWrite > 0
     {
         if (bytesToWrite == 0)
-            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
 
         size_t bytesWritten = 0;
         const int rv = ::SSL_write_ex(ssl_, buffer, bytesToWrite, &bytesWritten);
         if (rv != 1)
-            throw SysError(formatLastOpenSSLError(L"SSL_write_ex") + L" " + formatSslErrorRaw(::SSL_get_error(ssl_, rv)));
+            throw SysError(formatLastOpenSSLError(L"SSL_write_ex") + L' ' + formatSslErrorCode(::SSL_get_error(ssl_, rv)));
 
         if (bytesWritten > bytesToWrite)
             throw SysError(L"SSL_write_ex: buffer overflow.");
@@ -759,7 +764,7 @@ std::string zen::convertPuttyKeyToPkix(const std::string& keyStream, const std::
 
     auto numToBeString = [](size_t n) -> std::string
     {
-        static_assert(usingLittleEndian()&& sizeof(n) >= 4);
+        static_assert(usingLittleEndian() && sizeof(n) >= 4);
         const char* numStr = reinterpret_cast<const char*>(&n);
         return { numStr[3], numStr[2], numStr[1], numStr[0] }; //big endian!
     };
diff --git a/zen/perf.h b/zen/perf.h
index b6cb5bb0..9f368016 100644
--- a/zen/perf.h
+++ b/zen/perf.h
@@ -98,7 +98,7 @@ public:
 
         const int64_t timeMs = std::chrono::duration_cast<std::chrono::milliseconds>(watch_.elapsed()).count();
         const std::string msg = numberTo<std::string>(timeMs) + " ms";
-        std::clog << "Perf: duration: " << msg << "\n";
+        std::clog << "Perf: duration: " << msg << '\n';
         resultShown_ = true;
     }
 
diff --git a/zen/recycler.cpp b/zen/recycler.cpp
index dc156a6f..f4fd870b 100644
--- a/zen/recycler.cpp
+++ b/zen/recycler.cpp
@@ -45,7 +45,9 @@ bool zen::recycleOrDeleteIfExists(const Zstring& itemPath) //throw FileError
             return true;
         }
 
-        throw FileError(errorMsg, formatSystemError(L"g_file_trash", replaceCpy(_("Error Code %x"), L"%x", numberTo<std::wstring>(error->code)), utfTo<std::wstring>(error->message)));
+        throw FileError(errorMsg, formatSystemError(L"g_file_trash",
+                                                    replaceCpy(_("Error Code %x"), L"%x", numberTo<std::wstring>(error->code)),
+                                                    utfTo<std::wstring>(error->message)));
         //g_quark_to_string(error->domain)
     }
     return true;
diff --git a/zen/serialize.h b/zen/serialize.h
index dd884e3b..1eabcdec 100644
--- a/zen/serialize.h
+++ b/zen/serialize.h
@@ -25,35 +25,6 @@ namespace zen
 binary container for data storage: must support "basic" std::vector interface (e.g. std::vector<std::byte>, std::string, Zbase<char>)
 */
 
-//binary container reference implementations
-using Utf8String = Zbase<char>; //ref-counted + COW text stream + guaranteed performance: exponential growth
-class ByteArray;                //ref-counted       byte stream + guaranteed performance: exponential growth -> no COW, but 12% faster than Utf8String (due to no null-termination?)
-
-
-class ByteArray //essentially a std::vector<std::byte> with ref-counted semantics, but no COW! => *almost* value type semantics, but not quite
-{
-public:
-    using value_type     = std::vector<std::byte>::value_type;
-    using iterator       = std::vector<std::byte>::iterator;
-    using const_iterator = std::vector<std::byte>::const_iterator;
-
-    iterator begin() { return buffer_.ref().begin(); }
-    iterator end  () { return buffer_.ref().end  (); }
-
-    const_iterator begin() const { return buffer_.ref().begin(); }
-    const_iterator end  () const { return buffer_.ref().end  (); }
-
-    void resize(size_t len) { buffer_.ref().resize(len); }
-    size_t size() const { return buffer_.ref().size(); }
-    bool  empty() const { return buffer_.ref().empty(); }
-
-    inline friend bool operator==(const ByteArray& lhs, const ByteArray& rhs) { return lhs.buffer_.ref() == rhs.buffer_.ref(); }
-
-private:
-    SharedRef<std::vector<std::byte>> buffer_ = makeSharedRef<std::vector<std::byte>>();
-    //perf: shared_ptr indirection irrelevant: less than 1% slower!
-};
-
 /*
 -------------------------------
 |Buffered Input Stream Concept|
@@ -158,6 +129,7 @@ struct MemoryStreamOut
     }
 
     const BinContainer& ref() const { return buffer_; }
+    /**/  BinContainer& ref()       { return buffer_; }
 
 private:
     MemoryStreamOut           (const MemoryStreamOut&) = delete;
@@ -180,7 +152,7 @@ void bufferedStreamCopy(BufferedInputStream& streamIn,   //throw X
 {
     const size_t blockSize = streamIn.getBlockSize();
     if (blockSize == 0)
-        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
 
     std::vector<std::byte> buffer(blockSize);
     for (;;)
@@ -201,7 +173,7 @@ BinContainer bufferedLoad(BufferedInputStream& streamIn) //throw X
 
     const size_t blockSize = streamIn.getBlockSize();
     if (blockSize == 0)
-        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
 
     BinContainer buffer;
     for (;;)
@@ -238,7 +210,7 @@ void writeContainer(BufferedOutputStream& stream, const C& cont) //don't even co
     const auto len = cont.size();
     writeNumber(stream, static_cast<uint32_t>(len));
     if (len > 0)
-        writeArray(stream, &*cont.begin(), sizeof(typename C::value_type) * len); //don't use c_str(), but access uniformly via STL interface
+        writeArray(stream, &cont[0], sizeof(typename C::value_type) * len); //don't use c_str(), but access uniformly via STL interface
 }
 
 
@@ -276,7 +248,7 @@ C readContainer(BufferedInputStream& stream) //throw UnexpectedEndOfStreamError
         catch (std::length_error&) { throw UnexpectedEndOfStreamError(); } //most likely this is due to data corruption!
         catch (   std::bad_alloc&) { throw UnexpectedEndOfStreamError(); } //
 
-        readArray(stream, &*cont.begin(), sizeof(typename C::value_type) * strLength); //throw UnexpectedEndOfStreamError
+        readArray(stream, &cont[0], sizeof(typename C::value_type) * strLength); //throw UnexpectedEndOfStreamError
     }
     return cont;
 }
diff --git a/zen/shell_execute.h b/zen/shell_execute.h
index 580c4558..faea4bd9 100644
--- a/zen/shell_execute.h
+++ b/zen/shell_execute.h
@@ -74,7 +74,7 @@ int shellExecute(const Zstring& command, ExecutionType type, bool hideConsole) /
 std::string getCommandOutput(const Zstring& command) //throw SysError
 {
     //https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man3/popen.3.html
-    FILE* pipe = ::popen(command.c_str(), "r"); 
+    FILE* pipe = ::popen(command.c_str(), "r");
     if (!pipe)
         THROW_LAST_SYS_ERROR(L"popen");
     ZEN_ON_SCOPE_EXIT(::pclose(pipe));
@@ -97,7 +97,7 @@ std::string getCommandOutput(const Zstring& command) //throw SysError
             output.resize(output.size() - (blockSize - bytesRead)); //caveat: unsigned arithmetics
     }
     while (!::feof(pipe));
-    
+
     return output;
 }
 }
diff --git a/zen/socket.h b/zen/socket.h
index 827d446b..3bd0a2a0 100644
--- a/zen/socket.h
+++ b/zen/socket.h
@@ -89,7 +89,7 @@ namespace
 size_t tryReadSocket(SocketType socket, void* buffer, size_t bytesToRead) //throw SysError; may return short, only 0 means EOF!
 {
     if (bytesToRead == 0) //"read() with a count of 0 returns zero" => indistinguishable from end of file! => check!
-        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
 
     int bytesReceived = 0;
     for (;;)
@@ -114,7 +114,7 @@ size_t tryReadSocket(SocketType socket, void* buffer, size_t bytesToRead) //thro
 size_t tryWriteSocket(SocketType socket, const void* buffer, size_t bytesToWrite) //throw SysError; may return short! CONTRACT: bytesToWrite > 0
 {
     if (bytesToWrite == 0)
-        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
 
     int bytesWritten = 0;
     for (;;)
diff --git a/zen/string_base.h b/zen/string_base.h
index 6c835c72..d2e00baf 100644
--- a/zen/string_base.h
+++ b/zen/string_base.h
@@ -221,6 +221,7 @@ public:
     Zbase();
     Zbase(const Char* str) : Zbase(str, str + strLength(str)) {} //implicit conversion from a C-string!
     Zbase(const Char* str, size_t len) : Zbase(str, str + len) {}
+    Zbase(size_t count, Char fillChar);
     Zbase(const Zbase& str);
     Zbase(Zbase&& tmp) noexcept;
     template <class InputIterator>
@@ -251,7 +252,8 @@ public:
     size_t length() const;
     size_t size  () const { return length(); }
     const Char* c_str() const { return rawStr_; } //C-string format with 0-termination
-    const Char operator[](size_t pos) const;
+    const Char& operator[](size_t pos) const;
+    /**/  Char& operator[](size_t pos);
     bool empty() const { return length() == 0; }
     void clear();
     size_t find (const Zbase& str, size_t pos = 0)    const; //
@@ -283,10 +285,11 @@ public:
     static const size_t npos = static_cast<size_t>(-1);
 
 private:
-    Zbase            (int) = delete; //
-    Zbase& operator= (int) = delete; //detect usage errors by creating an intentional ambiguity with "Char"
-    Zbase& operator+=(int) = delete; //
-    void   push_back (int) = delete; //
+    Zbase              (int) = delete; //
+    Zbase(size_t count, int) = delete; //
+    Zbase& operator=   (int) = delete; //detect usage errors by creating an intentional ambiguity with "Char"
+    Zbase& operator+=  (int) = delete; //
+    void   push_back   (int) = delete; //
 
     Char* rawStr_;
 };
@@ -360,6 +363,15 @@ Zbase<Char, SP>::Zbase(InputIterator first, InputIterator last)
 
 
 template <class Char, template <class> class SP> inline
+Zbase<Char, SP>::Zbase(size_t count, Char fillChar)
+{
+    rawStr_ = this->create(count);
+    std::fill(rawStr_, rawStr_ + count, fillChar);
+    rawStr_[count] = 0;
+}
+
+
+template <class Char, template <class> class SP> inline
 Zbase<Char, SP>::Zbase(const Zbase<Char, SP>& str)
 {
     rawStr_ = this->clone(str.rawStr_);
@@ -544,7 +556,15 @@ size_t Zbase<Char, SP>::length() const
 
 
 template <class Char, template <class> class SP> inline
-const Char Zbase<Char, SP>::operator[](size_t pos) const
+const Char& Zbase<Char, SP>::operator[](size_t pos) const
+{
+    assert(pos < length()); //design by contract! no runtime check!
+    return rawStr_[pos];
+}
+
+
+template <class Char, template <class> class SP> inline
+Char& Zbase<Char, SP>::operator[](size_t pos)
 {
     assert(pos < length()); //design by contract! no runtime check!
     return rawStr_[pos];
diff --git a/zen/string_tools.h b/zen/string_tools.h
index 5c444830..40a4ea52 100644
--- a/zen/string_tools.h
+++ b/zen/string_tools.h
@@ -167,8 +167,8 @@ Char asciiToLower(Char c)
 }
 
 
-template <class Char> inline
-Char asciiToUpper(Char c)
+    template <class Char> inline
+    Char asciiToUpper(Char c)
 {
     if (static_cast<Char>('a') <= c && c <= static_cast<Char>('z'))
                                     return static_cast<Char>(c - static_cast<Char>('a') + static_cast<Char>('A'));
@@ -182,13 +182,13 @@ inline int strcmpWithNulls(const char*    ptr1, const char*    ptr2, size_t num)
 inline int strcmpWithNulls(const wchar_t* ptr1, const wchar_t* ptr2, size_t num) { return std::wmemcmp(ptr1, ptr2, num); } //
 
 
-template <class Char> inline
-int strcmpAsciiNoCase(const Char* lhs, const Char* rhs, size_t len)
+template <class Char1, class Char2> inline
+int strcmpAsciiNoCase(const Char1* lhs, const Char2* rhs, size_t len)
 {
     while (len-- > 0)
     {
-        const Char charL = asciiToLower(*lhs++); //ordering: lower-case chars have higher code points than uppper-case
-        const Char charR = asciiToLower(*rhs++); //
+        const Char1 charL = asciiToLower(*lhs++); //ordering: lower-case chars have higher code points than uppper-case
+        const Char2 charR = asciiToLower(*rhs++); //
         if (charL != charR)
             return static_cast<unsigned int>(charL) - static_cast<unsigned int>(charR); //unsigned char-comparison is the convention!
         //unsigned underflow is well-defined!
diff --git a/zen/string_traits.h b/zen/string_traits.h
index f1269130..69d76b44 100644
--- a/zen/string_traits.h
+++ b/zen/string_traits.h
@@ -220,7 +220,8 @@ auto makeStringView(Iterator first, Iterator last)
                                             last - first);
 }
 
-template <class Iterator> inline auto makeStringView(Iterator first, size_t len) { return makeStringView(first, first + len); }
+template <class Iterator> inline
+auto makeStringView(Iterator first, size_t len) { return makeStringView(first, first + len); }
 }
 
 #endif //STRING_TRAITS_H_813274321443234
diff --git a/zen/sys_error.cpp b/zen/sys_error.cpp
index 2acaca1d..b802780b 100644
--- a/zen/sys_error.cpp
+++ b/zen/sys_error.cpp
@@ -4,3 +4,187 @@
 // * Copyright (C) Zenju (zenju AT freefilesync DOT org) - All Rights Reserved *
 // *****************************************************************************
 
+#include "sys_error.h"
+    #include <cstring>
+
+using namespace zen;
+
+
+
+
+std::wstring zen::getSystemErrorDescription(ErrorCode ec) //return empty string on error
+{
+    const ErrorCode currentError = getLastError(); //not necessarily == ec
+    ZEN_ON_SCOPE_EXIT(errno = currentError);
+
+    std::wstring errorMsg;
+    errorMsg = utfTo<std::wstring>(::strerror(ec));
+    return trimCpy(errorMsg); //Windows messages seem to end with a space...
+}
+
+
+namespace
+{
+std::wstring formatSystemErrorCode(ErrorCode ec)
+{
+    switch (ec) //pretty much all codes currently used on CentOS 7 and macOS 10.15
+    {
+            ZEN_CHECK_CASE_FOR_CONSTANT(EPERM);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOENT);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ESRCH);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EINTR);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EIO);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENXIO);
+            ZEN_CHECK_CASE_FOR_CONSTANT(E2BIG);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOEXEC);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EBADF);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ECHILD);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EAGAIN);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOMEM);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EACCES);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EFAULT);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOTBLK);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EBUSY);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EEXIST);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EXDEV);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENODEV);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOTDIR);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EISDIR);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EINVAL);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENFILE);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EMFILE);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOTTY);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ETXTBSY);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EFBIG);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOSPC);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ESPIPE);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EROFS);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EMLINK);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EPIPE);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EDOM);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ERANGE);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EDEADLK);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENAMETOOLONG);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOLCK);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOSYS);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOTEMPTY);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ELOOP);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOMSG);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EIDRM);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOSTR);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENODATA);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ETIME);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOSR);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EREMOTE);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOLINK);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EPROTO);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EMULTIHOP);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EBADMSG);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EOVERFLOW);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EILSEQ);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EUSERS);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOTSOCK);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EDESTADDRREQ);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EMSGSIZE);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EPROTOTYPE);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOPROTOOPT);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EPROTONOSUPPORT);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ESOCKTNOSUPPORT);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOTSUP);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EPFNOSUPPORT);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EAFNOSUPPORT);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EADDRINUSE);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EADDRNOTAVAIL);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENETDOWN);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENETUNREACH);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENETRESET);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ECONNABORTED);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ECONNRESET);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOBUFS);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EISCONN);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOTCONN);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ESHUTDOWN);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ETOOMANYREFS);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ETIMEDOUT);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ECONNREFUSED);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EHOSTDOWN);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EHOSTUNREACH);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EALREADY);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EINPROGRESS);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ESTALE);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EDQUOT);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ECANCELED);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EOWNERDEAD);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOTRECOVERABLE);
+
+            ZEN_CHECK_CASE_FOR_CONSTANT(ECHRNG);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EL2NSYNC);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EL3HLT);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EL3RST);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ELNRNG);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EUNATCH);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOCSI);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EL2HLT);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EBADE);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EBADR);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EXFULL);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOANO);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EBADRQC);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EBADSLT);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EBFONT);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENONET);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOPKG);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EADV);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ESRMNT);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ECOMM);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EDOTDOT);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOTUNIQ);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EBADFD);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EREMCHG);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ELIBACC);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ELIBBAD);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ELIBSCN);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ELIBMAX);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ELIBEXEC);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ERESTART);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ESTRPIPE);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EUCLEAN);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOTNAM);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENAVAIL);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EISNAM);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EREMOTEIO);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOMEDIUM);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EMEDIUMTYPE);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ENOKEY);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EKEYEXPIRED);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EKEYREVOKED);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EKEYREJECTED);
+            ZEN_CHECK_CASE_FOR_CONSTANT(ERFKILL);
+            ZEN_CHECK_CASE_FOR_CONSTANT(EHWPOISON);
+        default:
+            return replaceCpy(_("Error Code %x"), L"%x", numberTo<std::wstring>(ec));
+    }
+}
+}
+
+
+std::wstring zen::formatSystemError(const std::wstring& functionName, ErrorCode ec)
+{
+    return formatSystemError(functionName, formatSystemErrorCode(ec), getSystemErrorDescription(ec));
+}
+
+
+std::wstring zen::formatSystemError(const std::wstring& functionName, const std::wstring& errorCode, const std::wstring& errorMsg)
+{
+    std::wstring output = errorCode + L':';
+
+    const std::wstring errorMsgFmt = trimCpy(errorMsg);
+    if (!errorMsgFmt.empty())
+    {
+        output += L' ';
+        output += errorMsgFmt;
+    }
+
+    output += L" [" + functionName + L']';
+    return output;
+}
diff --git a/zen/sys_error.h b/zen/sys_error.h
index a9347bdd..6bef45ea 100644
--- a/zen/sys_error.h
+++ b/zen/sys_error.h
@@ -8,11 +8,10 @@
 #define SYS_ERROR_H_3284791347018951324534
 
 #include <string>
-#include "utf.h"
-#include "i18n.h"
 #include "scope_guard.h"
+#include "i18n.h"
+#include "utf.h"
 
-    #include <cstring>
     #include <cerrno>
 
 
@@ -23,9 +22,8 @@ namespace zen
 
 ErrorCode getLastError();
 
-std::wstring formatSystemError(const std::wstring& functionName, ErrorCode ec);
 std::wstring formatSystemError(const std::wstring& functionName, const std::wstring& errorCode, const std::wstring& errorMsg);
-
+std::wstring formatSystemError(const std::wstring& functionName, ErrorCode ec);
 
 
 //A low-level exception class giving (non-translated) detail information only - same conceptional level like "GetLastError()"!
@@ -47,11 +45,6 @@ private:
     do { const ErrorCode ecInternal = getLastError(); throw SysError(formatSystemError(functionName, ecInternal)); } while (false)
 
 
-//helper for error checking macros:
-inline bool validatBool(bool b) { return b; }
-inline bool validatBool(void* b) { return b != nullptr; }
-bool validatBool(int) = delete; //catch unintended bool conversions, e.g. HRESULT
-
 
 
 
@@ -59,56 +52,15 @@ bool validatBool(int) = delete; //catch unintended bool conversions, e.g. HRESUL
 inline
 ErrorCode getLastError()
 {
-    return errno; //don't use "::", errno is a macro!
+    return errno; //don't use "::" prefix, errno is a macro!
 }
 
 
-std::wstring formatSystemErrorRaw(long long) = delete; //intentional overload ambiguity to catch usage errors
-
-inline
-std::wstring formatSystemErrorRaw(ErrorCode ec) //return empty string on error
-{
-    const ErrorCode currentError = getLastError(); //not necessarily == lastError
-
-    std::wstring errorMsg;
-    ZEN_ON_SCOPE_EXIT(errno = currentError);
-
-    errorMsg = utfTo<std::wstring>(::strerror(ec));
-    trim(errorMsg); //Windows messages seem to end with a blank...
-
-    return errorMsg;
-}
+std::wstring getSystemErrorDescription(ErrorCode ec); //return empty string on error
+//intentional overload ambiguity to catch usage errors with HRESULT:
+std::wstring getSystemErrorDescription(long long) = delete;
 
 
-std::wstring formatSystemError(const std::wstring& functionName, long long lastError) = delete; //intentional overload ambiguity to catch usage errors with HRESULT!
-
-inline
-std::wstring formatSystemError(const std::wstring& functionName, ErrorCode ec)
-{
-    const std::wstring errorCode = numberTo<std::wstring>(ec);
-    const std::wstring errorDescr = formatSystemErrorRaw(ec);
-
-    return formatSystemError(functionName, replaceCpy(_("Error Code %x"), L"%x", errorCode), errorDescr);
-}
-
-
-inline
-std::wstring formatSystemError(const std::wstring& functionName, const std::wstring& errorCode, const std::wstring& errorMsg)
-{
-    std::wstring output = errorCode + L":";
-
-    const std::wstring errorMsgFmt = trimCpy(errorMsg);
-    if (!errorMsgFmt.empty())
-    {
-        output += L" ";
-        output += errorMsgFmt;
-    }
-
-    output += L" [" + functionName + L"]";
-
-    return output;
-}
-
 }
 
 #endif //SYS_ERROR_H_3284791347018951324534
diff --git a/zen/system.cpp b/zen/system.cpp
index 5945484f..9401b94f 100644
--- a/zen/system.cpp
+++ b/zen/system.cpp
@@ -44,6 +44,7 @@ namespace
 
 ComputerModel zen::getComputerModel() //throw FileError
 {
+    ComputerModel cm;
     try
     {
         auto tryGetInfo = [](const Zstring& filePath)
@@ -57,9 +58,33 @@ ComputerModel zen::getComputerModel() //throw FileError
             }
             catch (const FileError& e) { throw SysError(e.toString()); } //errors should be further enriched by context info => SysError
         };
-        return { tryGetInfo("/sys/devices/virtual/dmi/id/product_name"), //throw SysError
-                 tryGetInfo("/sys/devices/virtual/dmi/id/sys_vendor") }; //
+        cm.model  = tryGetInfo("/sys/devices/virtual/dmi/id/product_name"); //throw SysError
+        cm.vendor = tryGetInfo("/sys/devices/virtual/dmi/id/sys_vendor");   //
+
+        //clean up:
+        for (const char* dummyModel :
+             {
+                 "To Be Filled By O.E.M.", "Default string", "empty", "O.E.M", "OEM", "NA",
+                 "System Product Name", "Please change product name", "INVALID",
+             })
+            if (equalAsciiNoCase(cm.model, dummyModel))
+            {
+                cm.model.clear();
+                break;
+            }
+
+        for (const char* dummyVendor :
+             {
+                 "To Be Filled By O.E.M.", "Default string", "empty", "O.E.M", "OEM", "NA",
+                 "System manufacturer", "OEM Manufacturer",
+             })
+            if (equalAsciiNoCase(cm.vendor, dummyVendor))
+            {
+                cm.vendor.clear();
+                break;
+            }
 
+        return cm;
     }
     catch (const SysError& e) { throw FileError(_("Cannot get process information."), e.toString()); }
 }
@@ -73,7 +98,7 @@ std::wstring zen::getOsDescription() //throw FileError
     {
         const std::string osName    = trimCpy(getCommandOutput("lsb_release --id -s"     )); //throw SysError
         const std::string osVersion = trimCpy(getCommandOutput("lsb_release --release -s")); //
-        return utfTo<std::wstring>(osName + " " + osVersion); //e.g. "CentOS 7.7.1908"
+        return utfTo<std::wstring>(osName + ' ' + osVersion); //e.g. "CentOS 7.7.1908"
 
     }
     catch (const SysError& e) { throw FileError(_("Cannot get process information."), e.toString()); }
diff --git a/zen/thread.cpp b/zen/thread.cpp
index 49c6d9b3..6e8b8219 100644
--- a/zen/thread.cpp
+++ b/zen/thread.cpp
@@ -28,7 +28,7 @@ uint64_t getThreadIdNative()
     const pid_t tid = ::syscall(SYS_gettid); //no-fail
     //"Invalid thread and process IDs": https://devblogs.microsoft.com/oldnewthing/20040223-00/?p=40503
     //if (tid == 0) -> not sure this holds on Linux, too!
-    //    throw std::runtime_error(std::string(__FILE__) + "[" + numberTo<std::string>(__LINE__) + "] Failed to get thread ID.");
+    //    throw std::runtime_error(std::string(__FILE__) + '[' + numberTo<std::string>(__LINE__) + "] Failed to get thread ID.");
     static_assert(sizeof(uint64_t) >= sizeof(tid));
     return tid;
 }
diff --git a/zen/thread.h b/zen/thread.h
index d6cafab7..a1d5197c 100644
--- a/zen/thread.h
+++ b/zen/thread.h
@@ -149,7 +149,7 @@ class ThreadGroup
 {
 public:
     ThreadGroup(size_t threadCountMax, const std::string& groupName) : threadCountMax_(threadCountMax), groupName_(groupName)
-    { if (threadCountMax == 0) throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__)); }
+    { if (threadCountMax == 0) throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__)); }
 
     ~ThreadGroup()
     {
diff --git a/zen/time.h b/zen/time.h
index 27ce518f..9718e5f6 100644
--- a/zen/time.h
+++ b/zen/time.h
@@ -8,7 +8,7 @@
 #define TIME_H_8457092814324342453627
 
 #include <ctime>
-#include "string_tools.h"
+#include "zstring.h"
 
 
 namespace zen
@@ -24,7 +24,7 @@ struct TimeComp //replaces std::tm and SYSTEMTIME
 };
 inline bool operator==(const TimeComp& lhs, const TimeComp& rhs)
 {
-    return lhs.year == rhs.year && lhs.month == rhs.month  && lhs.day == rhs.day && lhs.hour == rhs.hour && lhs.minute == rhs.minute && lhs.second == rhs.second;
+    return lhs.second == rhs.second && lhs.minute == rhs.minute && lhs.hour == rhs.hour && lhs.day == rhs.day && lhs.month == rhs.month  && lhs.year == rhs.year;
 }
 inline bool operator!=(const TimeComp& lhs, const TimeComp& rhs) { return !(lhs == rhs); }
 
@@ -37,34 +37,26 @@ time_t   utcToTimeT(const TimeComp& tc);              //convert UTC time compone
 TimeComp getCompileTime(); //returns TimeComp() on error
 
 //----------------------------------------------------------------------------------------------------------------------------------
-
-/*
-format (current) date and time; example:
-        formatTime<std::wstring>(L"%Y|%m|%d"); -> "2011|10|29"
-        formatTime<std::wstring>(FORMAT_DATE); -> "2011-10-29"
-        formatTime<std::wstring>(FORMAT_TIME); -> "17:55:34"
-*/
-template <class String, class String2>
-String formatTime(const String2& format, const TimeComp& tc = getLocalTime()); //format as specified by "std::strftime", returns empty string on failure
+/* format (current) date and time; example:
+            formatTime(Zstr("%Y|%m|%d")); -> "2011|10|29"
+            formatTime(formatDateTag);    -> "2011-10-29"
+            formatTime(formatTimeTag);    -> "17:55:34"                       */
+Zstring formatTime(const Zchar* format, const TimeComp& tc = getLocalTime()); //format as specified by "std::strftime", returns empty string on failure
 
 //the "format" parameter of formatTime() is partially specialized with the following type tags:
-const struct FormatDateTag     {} FORMAT_DATE      = {}; //%x - locale dependent date representation: e.g. 8/23/2001
-const struct FormatTimeTag     {} FORMAT_TIME      = {}; //%X - locale dependent time representation: e.g. 2:55:02 PM
-const struct FormatDateTimeTag {} FORMAT_DATE_TIME = {}; //%c - locale dependent date and time:       e.g. 8/23/2001 2:55:02 PM
+const Zchar* const formatDateTag     = Zstr("%x"); //locale-dependent date representation: e.g. 8/23/2001
+const Zchar* const formatTimeTag     = Zstr("%X"); //locale-dependent time representation: e.g. 2:55:02 PM
+const Zchar* const formatDateTimeTag = Zstr("%c"); //locale-dependent date and time:       e.g. 8/23/2001 2:55:02 PM
 
-const struct FormatIsoDateTag     {} FORMAT_ISO_DATE      = {}; //%Y-%m-%d          - e.g. 2001-08-23
-const struct FormatIsoTimeTag     {} FORMAT_ISO_TIME      = {}; //%H:%M:%S          - e.g. 14:55:02
-const struct FormatIsoDateTimeTag {} FORMAT_ISO_DATE_TIME = {}; //%Y-%m-%d %H:%M:%S - e.g. 2001-08-23 14:55:02
+const Zchar* const formatIsoDateTag     = Zstr("%Y-%m-%d");          //e.g. 2001-08-23
+const Zchar* const formatIsoTimeTag     = Zstr("%H:%M:%S");          //e.g. 14:55:02
+const Zchar* const formatIsoDateTimeTag = Zstr("%Y-%m-%d %H:%M:%S"); //e.g. 2001-08-23 14:55:02
 
 //----------------------------------------------------------------------------------------------------------------------------------
-
-/*
-example: parseTime("%Y-%m-%d %H:%M:%S",  "2001-08-23 14:55:02");
-         parseTime(FORMAT_ISO_DATE_TIME, "2001-08-23 14:55:02");
-*/
+//example: parseTime("%Y-%m-%d %H:%M:%S",  "2001-08-23 14:55:02");
+//         parseTime(formatIsoDateTimeTag, "2001-08-23 14:55:02");
 template <class String, class String2>
 TimeComp parseTime(const String& format, const String2& str); //similar to ::strptime()
-
 //----------------------------------------------------------------------------------------------------------------------------------
 
 
@@ -118,68 +110,6 @@ TimeComp toZenTimeComponents(const std::tm& ctc)
 }
 
 
-template <class T>
-struct GetFormat; //get default time formats as char* or wchar_t*
-
-template <>
-struct GetFormat<FormatDateTag> //%x - locale dependent date representation: e.g. 08/23/01
-{
-    const char*    format(char)    const { return  "%x"; }
-    const wchar_t* format(wchar_t) const { return L"%x"; }
-};
-
-template <>
-struct GetFormat<FormatTimeTag> //%X - locale dependent time representation: e.g. 14:55:02
-{
-    const char*    format(char)    const { return  "%X"; }
-    const wchar_t* format(wchar_t) const { return L"%X"; }
-};
-
-template <>
-struct GetFormat<FormatDateTimeTag> //%c - locale dependent date and time:       e.g. Thu Aug 23 14:55:02 2001
-{
-    const char*    format(char)    const { return  "%c"; }
-    const wchar_t* format(wchar_t) const { return L"%c"; }
-};
-
-template <>
-struct GetFormat<FormatIsoDateTag> //%Y-%m-%d - e.g. 2001-08-23
-{
-    const char*    format(char)    const { return  "%Y-%m-%d"; }
-    const wchar_t* format(wchar_t) const { return L"%Y-%m-%d"; }
-};
-
-template <>
-struct GetFormat<FormatIsoTimeTag> //%H:%M:%S - e.g. 14:55:02
-{
-    const char*    format(char)    const { return  "%H:%M:%S"; }
-    const wchar_t* format(wchar_t) const { return L"%H:%M:%S"; }
-};
-
-template <>
-struct GetFormat<FormatIsoDateTimeTag> //%Y-%m-%d %H:%M:%S - e.g. 2001-08-23 14:55:02
-{
-    const char*    format(char)    const { return  "%Y-%m-%d %H:%M:%S"; }
-    const wchar_t* format(wchar_t) const { return L"%Y-%m-%d %H:%M:%S"; }
-};
-
-
-//strftime() craziness on invalid input:
-//  VS 2010: CRASH unless "_invalid_parameter_handler" is set: https://msdn.microsoft.com/en-us/library/ksazx244.aspx
-//  GCC: returns 0, apparently no crash. Still, considering some clib maintainer's comments, we should expect the worst!
-inline
-size_t strftimeWrap_impl(char* buffer, size_t bufferSize, const char* format, const std::tm* timeptr)
-{
-    return std::strftime(buffer, bufferSize, format, timeptr);
-}
-
-
-inline
-size_t strftimeWrap_impl(wchar_t* buffer, size_t bufferSize, const wchar_t* format, const std::tm* timeptr)
-{
-    return std::wcsftime(buffer, bufferSize, format, timeptr);
-}
-
 /*
 inline
 bool isValid(const std::tm& t)
@@ -203,35 +133,6 @@ bool isValid(const std::tm& t)
     //tm_isdst
 };
 */
-
-template <class CharType> inline
-size_t strftimeWrap(CharType* buffer, size_t bufferSize, const CharType* format, const std::tm* timeptr)
-{
-    return strftimeWrap_impl(buffer, bufferSize, format, timeptr);
-}
-
-
-struct UserDefinedFormatTag {};
-struct PredefinedFormatTag  {};
-
-template <class String, class String2> inline
-String formatTime(const String2& format, const TimeComp& tc, UserDefinedFormatTag) //format as specified by "std::strftime", returns empty string on failure
-{
-    std::tm ctc = toClibTimeComponents(tc);
-    std::mktime(&ctc); // unfortunately std::strftime() needs all elements of "struct tm" filled, e.g. tm_wday, tm_yday
-    //note: although std::mktime() explicitly expects "local time", calculating weekday and day of year *should* be time-zone and DST independent
-
-    GetCharTypeT<String> buffer[256] = {};
-    const size_t charsWritten = strftimeWrap(buffer, 256, strBegin(format), &ctc);
-    return String(buffer, charsWritten);
-}
-
-
-template <class String, class FormatType> inline
-String formatTime(FormatType, const TimeComp& tc, PredefinedFormatTag)
-{
-    return formatTime<String>(GetFormat<FormatType>().format(GetCharTypeT<String>()), tc, UserDefinedFormatTag());
-}
 }
 
 
@@ -298,28 +199,29 @@ TimeComp getCompileTime()
 }
 
 
-template <class String, class String2> inline
-String formatTime(const String2& format, const TimeComp& tc)
+inline
+Zstring formatTime(const Zchar* format, const TimeComp& tc)
 {
     if (tc == TimeComp()) //failure code from getLocalTime()
-        return String();
+        return Zstring();
 
-    using FormatTag = std::conditional_t<
-                      std::is_same_v<String2, FormatDateTag       > ||
-                      std::is_same_v<String2, FormatTimeTag       > ||
-                      std::is_same_v<String2, FormatDateTimeTag   > ||
-                      std::is_same_v<String2, FormatIsoDateTag    > ||
-                      std::is_same_v<String2, FormatIsoTimeTag    > ||
-                      std::is_same_v<String2, FormatIsoDateTimeTag>, impl::PredefinedFormatTag, impl::UserDefinedFormatTag>;
+    std::tm ctc = impl::toClibTimeComponents(tc);
+    std::mktime(&ctc); //unfortunately std::strftime() needs all elements of "struct tm" filled, e.g. tm_wday, tm_yday
+    //note: although std::mktime() explicitly expects "local time", calculating weekday and day of year *should* be time-zone and DST independent
 
-    return impl::formatTime<String>(format, tc, FormatTag());
+    Zstring buffer(256, Zstr('\0'));
+    //strftime() craziness on invalid input:
+    //  VS 2010: CRASH unless "_invalid_parameter_handler" is set: https://docs.microsoft.com/en-us/cpp/c-runtime-library/parameter-validation
+    //  GCC: returns 0, apparently no crash. Still, considering some clib maintainer's comments, we should expect the worst!
+    //  Windows: avoid char-based strftime() which uses ANSI encoding! (e.g. Greek letters for AM/PM)
+    const size_t charsWritten = std::strftime(&buffer[0], buffer.size(), format, &ctc);
+    buffer.resize(charsWritten);
+    return buffer;
 }
 
 
-namespace impl
-{
 template <class String, class String2>
-TimeComp parseTime(const String& format, const String2& str, UserDefinedFormatTag)
+TimeComp parseTime(const String& format, const String2& str)
 {
     using CharType = GetCharTypeT<String>;
     static_assert(std::is_same_v<CharType, GetCharTypeT<String2>>);
@@ -371,11 +273,9 @@ TimeComp parseTime(const String& format, const String2& str, UserDefinedFormatTa
                         return TimeComp();
 
                     const char* months[] = { "jan", "feb", "mar", "apr", "may", "jun", "jul", "aug", "sep", "oct", "nov", "dec" };
-                    auto itMonth = std::find_if(std::begin(months), std::end(months), [&](const char* name)
+                    auto itMonth = std::find_if(std::begin(months), std::end(months), [&](const char* month)
                     {
-                        return asciiToLower(itStr[0]) == name[0] &&
-                               asciiToLower(itStr[1]) == name[1] &&
-                               asciiToLower(itStr[2]) == name[2];
+                        return equalAsciiNoCase(makeStringView(itStr, 3), month);
                     });
                     if (itMonth == std::end(months))
                         return TimeComp();
@@ -422,26 +322,6 @@ TimeComp parseTime(const String& format, const String2& str, UserDefinedFormatTa
 
     return output;
 }
-
-
-template <class FormatType, class String>  inline
-TimeComp parseTime(FormatType, const String& str, PredefinedFormatTag)
-{
-    return parseTime(GetFormat<FormatType>().format(GetCharTypeT<String>()), str, UserDefinedFormatTag());
-}
-}
-
-
-template <class String, class String2> inline
-TimeComp parseTime(const String& format, const String2& str)
-{
-    using FormatTag = std::conditional_t<
-                      std::is_same_v<String, FormatIsoDateTag    > ||
-                      std::is_same_v<String, FormatIsoTimeTag    > ||
-                      std::is_same_v<String, FormatIsoDateTimeTag>, impl::PredefinedFormatTag, impl::UserDefinedFormatTag>;
-
-    return impl::parseTime(format, str, FormatTag());
-}
 }
 
 #endif //TIME_H_8457092814324342453627
diff --git a/zen/zlib_wrap.cpp b/zen/zlib_wrap.cpp
index 57a0f33c..685843c3 100644
--- a/zen/zlib_wrap.cpp
+++ b/zen/zlib_wrap.cpp
@@ -29,8 +29,10 @@ std::wstring formatZlibStatusCode(int sc)
             ZEN_CHECK_CASE_FOR_CONSTANT(Z_MEM_ERROR);
             ZEN_CHECK_CASE_FOR_CONSTANT(Z_BUF_ERROR);
             ZEN_CHECK_CASE_FOR_CONSTANT(Z_VERSION_ERROR);
+
+        default:
+            return replaceCpy<std::wstring>(L"zlib status %x", L"%x", numberTo<std::wstring>(sc));
     }
-    return replaceCpy<std::wstring>(L"zlib status %x.", L"%x", numberTo<std::wstring>(sc));
 }
 }
 
@@ -53,7 +55,7 @@ size_t zen::impl::zlib_compress(const void* src, size_t srcLen, void* trg, size_
     // Z_MEM_ERROR: not enough memory
     // Z_BUF_ERROR: not enough room in the output buffer
     if (rv != Z_OK || bufferSize > trgLen)
-        throw SysError(formatSystemError(L"compress2", formatZlibStatusCode(rv), L"zlib error"));
+        throw SysError(formatSystemError(L"zlib compress2", formatZlibStatusCode(rv), L""));
 
     return bufferSize;
 }
@@ -71,7 +73,7 @@ size_t zen::impl::zlib_decompress(const void* src, size_t srcLen, void* trg, siz
     // Z_BUF_ERROR: not enough room in the output buffer
     // Z_DATA_ERROR: input data was corrupted or incomplete
     if (rv != Z_OK || bufferSize > trgLen)
-        throw SysError(formatSystemError(L"uncompress", formatZlibStatusCode(rv), L"zlib error"));
+        throw SysError(formatSystemError(L"zlib uncompress", formatZlibStatusCode(rv), L""));
 
     return bufferSize;
 }
@@ -96,7 +98,7 @@ public:
                                       memLevel,              //int memLevel
                                       Z_DEFAULT_STRATEGY);   //int strategy
         if (rv != Z_OK)
-            throw SysError(formatSystemError(L"deflateInit2", formatZlibStatusCode(rv), L"zlib error"));
+            throw SysError(formatSystemError(L"zlib deflateInit2", formatZlibStatusCode(rv), L""));
     }
 
     ~Impl()
@@ -108,7 +110,7 @@ public:
     size_t read(void* buffer, size_t bytesToRead) //throw SysError, X; return "bytesToRead" bytes unless end of stream!
     {
         if (bytesToRead == 0) //"read() with a count of 0 returns zero" => indistinguishable from end of file! => check!
-            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
 
         gzipStream_.next_out  = static_cast<Bytef*>(buffer);
         gzipStream_.avail_out = static_cast<uInt>(bytesToRead);
@@ -131,7 +133,7 @@ public:
             if (rv == Z_STREAM_END)
                 return bytesToRead - gzipStream_.avail_out;
             if (rv != Z_OK)
-                throw SysError(formatSystemError(L"deflate", formatZlibStatusCode(rv), L"zlib error"));
+                throw SysError(formatSystemError(L"zlib deflate", formatZlibStatusCode(rv), L""));
 
             if (gzipStream_.avail_out == 0)
                 return bytesToRead;
diff --git a/zen/zlib_wrap.h b/zen/zlib_wrap.h
index b820a4f8..3db609da 100644
--- a/zen/zlib_wrap.h
+++ b/zen/zlib_wrap.h
@@ -63,7 +63,7 @@ BinContainer compress(const BinContainer& stream, int level) //throw SysError
         //save uncompressed stream size for decompression
         const uint64_t uncompressedSize = stream.size(); //use portable number type!
         contOut.resize(sizeof(uncompressedSize));
-        std::memcpy(&*contOut.begin(), &uncompressedSize, sizeof(uncompressedSize));
+        std::memcpy(&contOut[0], &uncompressedSize, sizeof(uncompressedSize));
 
         const size_t bufferEstimate = impl::zlib_compressBound(stream.size()); //upper limit for buffer size, larger than input size!!!
 
@@ -105,8 +105,8 @@ BinContainer decompress(const BinContainer& stream) //throw SysError
             contOut.resize(static_cast<size_t>(uncompressedSize)); //throw std::bad_alloc
         }
         //most likely this is due to data corruption:
-        catch (const std::length_error& e) { throw SysError(L"zlib error: " + _("Out of memory.") + L" " + utfTo<std::wstring>(e.what())); }
-        catch (const    std::bad_alloc& e) { throw SysError(L"zlib error: " + _("Out of memory.") + L" " + utfTo<std::wstring>(e.what())); }
+        catch (const std::length_error& e) { throw SysError(L"zlib error: " + _("Out of memory.") + L' ' + utfTo<std::wstring>(e.what())); }
+        catch (const    std::bad_alloc& e) { throw SysError(L"zlib error: " + _("Out of memory.") + L' ' + utfTo<std::wstring>(e.what())); }
 
         const size_t bytesWritten = impl::zlib_decompress(&*stream.begin() + sizeof(uncompressedSize),
                                                           stream.size() - sizeof(uncompressedSize),
diff --git a/zen/zstring.cpp b/zen/zstring.cpp
index ff20b8cf..046a3bd4 100644
--- a/zen/zstring.cpp
+++ b/zen/zstring.cpp
@@ -50,7 +50,8 @@ Zstring getUnicodeNormalForm(const Zstring& str)
 {
     //fast pre-check:
     if (isAsciiString(str)) //perf: in the range of 3.5ns
-        return str; //god bless our ref-counting! => save output string memory consumption!
+        return str;
+    static_assert(std::is_same_v<decltype(str), const Zbase<Zchar>&>, "god bless our ref-counting! => save output string memory consumption!");
 
     //Example: const char* decomposed  = "\x6f\xcc\x81";
     //         const char* precomposed = "\xc3\xb3";
diff --git a/zen/zstring.h b/zen/zstring.h
index f24e4299..d5d8c588 100644
--- a/zen/zstring.h
+++ b/zen/zstring.h
@@ -19,8 +19,9 @@
 //a high-performance string for interfacing with native OS APIs in multithreaded contexts
 using Zstring = zen::Zbase<Zchar>;
 
-//for special UI-contexts: guaranteed exponential growth + ref-counting
-using Zstringw = zen::Zbase<wchar_t>;
+//for special UI-contexts: guaranteed exponential growth + ref-counting + COW + no SSO overhead
+using Zstringc = zen::Zbase<char>;
+//using Zstringw = zen::Zbase<wchar_t>;
 
 
 //Caveat: don't expect input/output string sizes to match:
@@ -34,7 +35,7 @@ Zstring makeUpperCopy(const Zstring& str);
 Zstring getUnicodeNormalForm(const Zstring& str);
 //  "In fact, Unicode declares that there is an equivalence relationship between decomposed and composed sequences,
 //  and conformant software should not treat canonically equivalent sequences, whether composed or decomposed or something in between, as different."
-//                                                                                          http://www.win.tue.nl/~aeb/linux/uc/nfc_vs_nfd.html
+//  http://www.win.tue.nl/~aeb/linux/uc/nfc_vs_nfd.html
 
 struct LessUnicodeNormal { bool operator()(const Zstring& lhs, const Zstring& rhs) const { return getUnicodeNormalForm(lhs) < getUnicodeNormalForm(rhs);} };
 
diff --git a/zenXml/zenxml/cvrt_struc.h b/zenXml/zenxml/cvrt_struc.h
index 9df1c7ba..45109187 100644
--- a/zenXml/zenxml/cvrt_struc.h
+++ b/zenXml/zenxml/cvrt_struc.h
@@ -57,11 +57,11 @@ ZEN_INIT_DETECT_MEMBER(insert) //
 
 template <typename T>
 using IsStlContainer = std::bool_constant<
-                       impl_2384343::HasMemberTypeV_value_type    <T> &&
-                       impl_2384343::HasMemberTypeV_iterator      <T> &&
-                       impl_2384343::HasMemberTypeV_const_iterator<T> &&
-                       impl_2384343::HasMemberV_begin             <T> &&
-                       impl_2384343::HasMemberV_end               <T> &&
+                       impl_2384343::HasMemberTypeV_value_type    <T>&&
+                       impl_2384343::HasMemberTypeV_iterator      <T>&&
+                       impl_2384343::HasMemberTypeV_const_iterator<T>&&
+                       impl_2384343::HasMemberV_begin             <T>&&
+                       impl_2384343::HasMemberV_end               <T>&&
                        impl_2384343::HasMemberV_insert            <T>>;
 
 
diff --git a/zenXml/zenxml/dom.h b/zenXml/zenxml/dom.h
index 0f456822..35226fc7 100644
--- a/zenXml/zenxml/dom.h
+++ b/zenXml/zenxml/dom.h
@@ -230,7 +230,7 @@ public:
       \code
         auto iterPair = elem.getAttributes();
         for (auto it = iterPair.first; it != iterPair.second; ++it)
-           std::cout << "name: " << it->name << " value: " << it->value << "\n";
+           std::cout << "name: " << it->name << " value: " << it->value << '\n';
       \endcode
       \return A pair of STL begin/end iterators to access all attributes sequentially as a list of name/value pairs of std::string.
     */
diff --git a/zenXml/zenxml/xml.h b/zenXml/zenxml/xml.h
index 80b60730..4058f7bf 100644
--- a/zenXml/zenxml/xml.h
+++ b/zenXml/zenxml/xml.h
@@ -369,8 +369,8 @@ public:
     {
         std::vector<String> output;
 
-		for (const std::string& str : log_.ref().elementList())
-			output.push_back(utfTo<String>(str));
+        for (const std::string& str : log_.ref().elementList())
+            output.push_back(utfTo<String>(str));
 
         return output;
     }
@@ -382,7 +382,7 @@ private:
 
     static std::string getNameFormatted(const XmlElement& elem) //"<Root> <Level1> <Level2>"
     {
-        return (elem.parent() ? getNameFormatted(*elem.parent()) + " " : std::string()) + "<" + elem.getNameAs<std::string>() + ">";
+        return (elem.parent() ? getNameFormatted(*elem.parent()) + ' ' : std::string()) + '<' + elem.getNameAs<std::string>() + '>';
     }
 
     std::string getNameFormatted() const
@@ -399,7 +399,7 @@ private:
     std::string getChildNameFormatted(const std::string& childName) const
     {
         std::string parentName = getNameFormatted();
-        return (parentName.empty() ? std::string() : (parentName + " ")) + "<" + childName + ">";
+        return (parentName.empty() ? std::string() : (parentName + ' ')) + '<' + childName + '>';
     }
 
     class ErrorLog
@@ -440,9 +440,9 @@ void checkXmlMappingErrors(const XmlIn& xmlInput, const Zstring& filePath) //thr
 {
     if (xmlInput.haveErrors())
     {
-        std::wstring msg = _("The following XML elements could not be read:") + L"\n";
+        std::wstring msg = _("The following XML elements could not be read:") + L'\n';
         for (const std::wstring& elem : xmlInput.getErrorsAs<std::wstring>())
-            msg += L"\n" + elem;
+            msg += L'\n' + elem;
 
         throw FileError(replaceCpy(_("Configuration file %x is incomplete. The missing elements will be set to their default values."), L"%x", fmtPath(filePath)) + L"\n\n" + msg);
     }