diff --git a/widget/gtk/nsWindow.cpp b/widget/gtk/nsWindow.cpp
--- a/widget/gtk/nsWindow.cpp
+++ b/widget/gtk/nsWindow.cpp
@@ -3238,16 +3238,18 @@ void nsWindow::OnWindowStateEvent(GtkWid
   // We don't care about anything but changes in the maximized/icon/fullscreen
   // states
   if ((aEvent->changed_mask &
        (GDK_WINDOW_STATE_ICONIFIED | GDK_WINDOW_STATE_MAXIMIZED |
         GDK_WINDOW_STATE_FULLSCREEN)) == 0) {
     return;
   }
 
+  nsSizeMode lastSizeState = mSizeState;
+
   if (aEvent->new_window_state & GDK_WINDOW_STATE_ICONIFIED) {
     LOG(("\tIconified\n"));
     mSizeState = nsSizeMode_Minimized;
 #ifdef ACCESSIBILITY
     DispatchMinimizeEventAccessible();
 #endif  // ACCESSIBILITY
   } else if (aEvent->new_window_state & GDK_WINDOW_STATE_FULLSCREEN) {
     LOG(("\tFullscreen\n"));
@@ -3261,16 +3263,28 @@ void nsWindow::OnWindowStateEvent(GtkWid
   } else {
     LOG(("\tNormal\n"));
     mSizeState = nsSizeMode_Normal;
 #ifdef ACCESSIBILITY
     DispatchRestoreEventAccessible();
 #endif  // ACCESSIBILITY
   }
 
+  // Fullscreen video playback may generate bogus alpha values which blends
+  // with desktop background in fullscreen video playback (Bug 1568569).
+  // As a workaround enable to draw mShell background in fullscreen mode
+  // if we draw to mContainer.
+  if (gtk_widget_get_has_window(GTK_WIDGET(mContainer))) {
+    if (mSizeState == nsSizeMode_Fullscreen) {
+      gtk_widget_set_app_paintable(mShell, FALSE);
+    } else if (lastSizeState == nsSizeMode_Fullscreen) {
+      gtk_widget_set_app_paintable(mShell, TRUE);
+    }
+  }
+
   if (mWidgetListener) {
     mWidgetListener->SizeModeChanged(mSizeState);
     if (aEvent->changed_mask & GDK_WINDOW_STATE_FULLSCREEN) {
       mWidgetListener->FullscreenChanged(aEvent->new_window_state &
                                          GDK_WINDOW_STATE_FULLSCREEN);
     }
   }
 
@@ -3787,16 +3801,21 @@ nsresult nsWindow::Create(nsIWidget* aPa
       eventWidget = (drawToContainer) ? container : mShell;
 
       // Prevent GtkWindow from painting a background to avoid flickering.
       gtk_widget_set_app_paintable(eventWidget, TRUE);
 
       gtk_widget_add_events(eventWidget, kEvents);
       if (drawToContainer) {
         gtk_widget_add_events(mShell, GDK_PROPERTY_CHANGE_MASK);
+        // Don't paint mShell background when we draw to mContainer.
+        // Otherwise we see mShell backround to shine through
+        // mContainer (Bug 1507608).
+        // But it may also lead to various bugs where mContainer has unintended
+        // transparent parts which blend with underlying desktop (Bug 1516224).
         gtk_widget_set_app_paintable(mShell, TRUE);
       }
       if (mTransparencyBitmapForTitlebar) {
         moz_container_force_default_visual(mContainer);
       }
 
       // If we draw to mContainer window then configure it now because
       // gtk_container_add() realizes the child widget.