3 files changed, 45 insertions, 2 deletions

diff --git a/src-qt5/core/libLumina/LDesktopUtils.cpp b/src-qt5/core/libLumina/LDesktopUtils.cpp
index a46f03d0..d76c68e9 100644
--- a/src-qt5/core/libLumina/LDesktopUtils.cpp
+++ b/src-qt5/core/libLumina/LDesktopUtils.cpp
@@ -9,6 +9,7 @@
 #include <QDesktopWidget>
 #include <QApplication>
 #include <QScreen>
+#include <QSettings>
 
 #include "LuminaThemes.h"
 
@@ -526,3 +527,19 @@ int LDesktopUtils::VersionStringToNumber(QString version){
   //NOTE: This format allows numbers to be anywhere from 0->999 without conflict
   return (maj*1000000 + mid*1000 + min);
 }
+
+void LDesktopUtils::MigrateDesktopSettings(QSettings *settings, QString fromID, QString toID){
+  //desktop-ID
+  QStringList keys = settings->allKeys();
+  QStringList filter = keys.filter("desktop-"+fromID+"/");
+  for(int i=0; i<filter.length(); i++){
+    settings->setValue("desktop-"+toID+"/"+filter[i].section("/",1,-1), settings->value(filter[i]));
+    settings->remove(filter[i]);
+  }
+  //panel_ID.[number]
+  filter = keys.filter("panel_"+fromID+".");
+  for(int i=0; i<filter.length(); i++){
+    settings->setValue("panel_"+toID+"."+ filter[i].section("/",0,0).section(".",-1)+"/"+filter[i].section("/",1,-1), settings->value(filter[i]));
+    settings->remove(filter[i]);
+  }
+}
diff --git a/src-qt5/core/libLumina/LDesktopUtils.h b/src-qt5/core/libLumina/LDesktopUtils.h
index dbad8757..b21bc78a 100644
--- a/src-qt5/core/libLumina/LDesktopUtils.h
+++ b/src-qt5/core/libLumina/LDesktopUtils.h
@@ -12,6 +12,7 @@
 #include <QFile>
 #include <QDir>
 #include <QDateTime>
+#include <QSettings>
 
 //Other classes needed
 #include <LUtils.h>
@@ -44,6 +45,10 @@ public:
 	static void LoadSystemDefaults(bool skipOS = false);
 	static bool checkUserFiles(QString lastversion); //returns true if something changed
 	static int VersionStringToNumber(QString version); //convert the lumina version string to a number for comparisons
+
+	//Migrating desktop settings from one ID to another
+	static void MigrateDesktopSettings(QSettings *settings, QString fromID, QString toID);
+
 };
 
 #endif
diff --git a/src-qt5/core/lumina-desktop/LSession.cpp b/src-qt5/core/lumina-desktop/LSession.cpp
index 735390aa..8932ac36 100644
--- a/src-qt5/core/lumina-desktop/LSession.cpp
+++ b/src-qt5/core/lumina-desktop/LSession.cpp
@@ -403,6 +403,25 @@ void LSession::updateDesktops(){
 
   bool firstrun = (DESKTOPS.length()==0);
   bool numchange = DESKTOPS.length()!=sC;
+  QSettings dset("lumina-desktop", "desktopsettings");
+  if(firstrun && sC==1){
+    //Sanity check - ensure the monitor ID did not change between sessions for single-monitor setups
+    QString name = QApplication::screens().at(0)->name();
+    if(!dset.contains("desktop-"+name+"/screen/lastHeight")){
+      //Empty Screen - find the previous one and migrate the settings over
+      QStringList old = dset.allKeys().filter("desktop-").filter("/screen/lastHeight");
+	QStringList lastused = dset.value("last_used_screens").toStringList();
+      QString oldname;
+      for(int i=0; i<old.length(); i++){
+        QString tmp = old[i].section("/",0,0).section("-",1,-1); //old desktop ID
+        if(tmp=="default"){ continue; } //always skip this one
+        else if(lastused.contains(tmp)){
+          oldname = tmp; break; //use the first screen that was last used
+        }
+      }
+      if(!oldname.isEmpty()){ LDesktopUtils::MigrateDesktopSettings(&dset, oldname, name); }
+    }
+  }
 
   // If the screen count is changing on us
   if ( sC != DW->screenCount() ) {
@@ -431,7 +450,10 @@ void LSession::updateDesktops(){
   }
   
   //Now add any new desktops
+  QStringList allNames;
+  QList<QScreen*> scrns = QApplication::screens();
   for(int i=0; i<sC; i++){
+    allNames << scrns.at(i)->name();
     if(!dnums.contains(i) && !geoms.contains(DW->screenGeometry(i)) ){
       //Start the desktop on this screen
       qDebug() << " - Start desktop on screen:" << i;
@@ -439,7 +461,7 @@ void LSession::updateDesktops(){
       geoms << DW->screenGeometry(i);
     }
   }
-  
+  dset.setValue("last_used_screens", allNames);
   //Make sure fluxbox also gets prompted to re-load screen config if the number of screens changes in the middle of a session
     if(numchange && !firstrun) {
       qDebug() << "Update WM";
@@ -449,7 +471,6 @@ void LSession::updateDesktops(){
   //Make sure all the background windows are registered on the system as virtual roots
   QTimer::singleShot(100,this, SLOT(registerDesktopWindows()));
   //Determine if any High-DPI screens are available and enable auto-scaling as needed
-  QList<QScreen*> scrns = QApplication::screens();
   for(int i=0; i<scrns.length(); i++){
     qDebug() << "Check Screen DPI:" << scrns[i]->name();
     qDebug() << " -- Physical DPI:" << scrns[i]->physicalDotsPerInchX() << "x" << scrns[i]->physicalDotsPerInchY();