diff -up firefox-88.0/dom/base/test/browser_multiple_popups.js.mochitest-wayland-workaround firefox-88.0/dom/base/test/browser_multiple_popups.js
--- firefox-88.0/dom/base/test/browser_multiple_popups.js.mochitest-wayland-workaround	2021-04-15 21:44:27.000000000 +0200
+++ firefox-88.0/dom/base/test/browser_multiple_popups.js	2021-04-22 15:17:36.905908990 +0200
@@ -265,6 +265,7 @@ add_task(async _ => {
   info("All opened from chrome.");
   await withTestPage(2, { chrome: true }, async function(browser) {
     await BrowserTestUtils.synthesizeMouseAtCenter("#openPopups", {}, browser);
+    await BrowserTestUtils.synthesizeMouseAtCenter("#openPopups", {}, browser);
   });
 });
 
diff -up firefox-88.0/dom/ipc/BrowserChild.cpp.mochitest-wayland-workaround firefox-88.0/dom/ipc/BrowserChild.cpp
--- firefox-88.0/dom/ipc/BrowserChild.cpp.mochitest-wayland-workaround	2021-04-16 01:11:48.000000000 +0200
+++ firefox-88.0/dom/ipc/BrowserChild.cpp	2021-04-22 15:17:36.905908990 +0200
@@ -459,7 +459,7 @@ nsresult BrowserChild::Init(mozIDOMWindo
   }
   mPuppetWidget->InfallibleCreate(nullptr,
                                   nullptr,  // no parents
-                                  LayoutDeviceIntRect(0, 0, 0, 0),
+                                  LayoutDeviceIntRect(0, 0, 1000, 1000),
                                   nullptr);  // HandleWidgetEvent
 
   mWebBrowser = nsWebBrowser::Create(this, mPuppetWidget, mBrowsingContext,
diff -up firefox-88.0/toolkit/components/browser/nsWebBrowser.cpp.mochitest-wayland-workaround firefox-88.0/toolkit/components/browser/nsWebBrowser.cpp
--- firefox-88.0/toolkit/components/browser/nsWebBrowser.cpp.mochitest-wayland-workaround	2021-04-16 01:11:48.000000000 +0200
+++ firefox-88.0/toolkit/components/browser/nsWebBrowser.cpp	2021-04-22 15:17:36.905908990 +0200
@@ -147,7 +147,8 @@ already_AddRefed<nsWebBrowser> nsWebBrow
   // handler that always gets called (even for subframes) for any bubbling
   // event.
 
-  nsresult rv = docShell->InitWindow(nullptr, docShellParentWidget, 0, 0, 0, 0);
+  nsresult rv =
+      docShell->InitWindow(nullptr, docShellParentWidget, 0, 0, 1000, 1000);
   if (NS_WARN_IF(NS_FAILED(rv))) {
     return nullptr;
   }
diff -up firefox-88.0/widget/gtk/nsWindow.cpp.mochitest-wayland-workaround firefox-88.0/widget/gtk/nsWindow.cpp
--- firefox-88.0/widget/gtk/nsWindow.cpp.mochitest-wayland-workaround	2021-04-22 15:17:36.903908930 +0200
+++ firefox-88.0/widget/gtk/nsWindow.cpp	2021-04-22 15:23:27.031343692 +0200
@@ -2224,8 +2224,22 @@ void nsWindow::SetFocus(Raise aRaise, mo
           Preferences::GetBool("widget.wayland-focus-workaroud", false)) {
         // Wayland does not support focus changes so we need to workaround it
         // by window hide/show sequence.
-        owningWindow->NativeShow(false);
-        owningWindow->NativeShow(true);
+        LOG(("Applying Wayland focus workaround for nsWindow %p\n",
+             owningWindow.get()));
+        GtkAllocation allocation;
+        gtk_widget_get_allocation(GTK_WIDGET(mContainer), &allocation);
+        LOG(("    mShell allocation %d %d -> %d %d\n", allocation.x,
+             allocation.y, allocation.width, allocation.height));
+        owningWindow->Show(false);
+        RefPtr<nsWindow> self(owningWindow);
+        const GtkAllocation alloc = allocation;
+        NS_DispatchToMainThread(
+            NS_NewRunnableFunction("nsWindow::Show()", [self, alloc]() -> void {
+              self->Show(true);
+              GtkAllocation al = alloc;
+              self->mBounds.width = self->mBounds.height = 1;
+              self->OnSizeAllocate(&al);
+            }));
         return;
       }
 
@@ -7935,6 +7949,8 @@ nsresult nsWindow::SynthesizeNativeMouse
     nsIObserver* aObserver) {
   AutoObserverNotifier notifier(aObserver, "mouseevent");
 
+  LOG(("nsWindow::SynthesizeNativeMouseEvent [%p]\n", (void*)this));
+
   if (!mGdkWindow) {
     return NS_OK;
   }
@@ -7949,6 +7965,12 @@ nsresult nsWindow::SynthesizeNativeMouse
   switch (aNativeMessage) {
     case NativeMouseMessage::ButtonDown:
     case NativeMouseMessage::ButtonUp: {
+      if (aNativeMessage == NativeMouseMessage::ButtonDown) {
+        LOG(("    NativeMouseMessage::ButtonDown()\n"));
+      } else {
+        LOG(("    NativeMouseMessage::ButtonUp()\n"));
+      }
+
       GdkEvent event;
       memset(&event, 0, sizeof(GdkEvent));
       event.type = aNativeMessage == NativeMouseMessage::ButtonDown