Win32: Tweaked widget sizing after mode switches

It appears on Windows a visible fullscreen QWidget does not update its geometry
when the display mode changes, so in this situation we'll briefly switch it to
normal show mode and then back to fullscreen mode.

Todo: Check if this approach works on OS X as well.

doomsday/engine/portable/src/window.cpp

@@ -56,7 +56,7 @@
 #ifdef MACOSX
 static const int POST_MODE_CHANGE_WAIT_BEFORE_UPDATE = 100; // ms
 #else
-static const int POST_MODE_CHANGE_WAIT_BEFORE_UPDATE = 1; // ms
+static const int POST_MODE_CHANGE_WAIT_BEFORE_UPDATE = 10; // ms
 #endif
 
 /// Used to determine the valid region for windows on the desktop.
@@ -83,6 +83,7 @@ struct ddwindow_s
     void (*drawFunc)(void); ///< Draws the contents of the canvas.
     QRect appliedGeometry;  ///< Saved for detecting when changes have occurred.
     bool needShowFullscreen;
+    bool needReshowFullscreen;
     bool needShowNormal;
 
     ddwindowtype_t type;
@@ -214,24 +215,40 @@ struct ddwindow_s
      */
     void applyWindowGeometry()
     {
+        LOG_AS("applyWindowGeometry");
+
         assertWindow();
 
         bool modeChanged = applyDisplayMode();
 
         if(flags & DDWF_FULLSCREEN)
         {
+            LOG_DEBUG("fullscreen mode (mode changed? %b)") << modeChanged;
+
             if(!modeChanged) return; // We don't need to do anything.
 
             if(widget->isVisible())
             {
                 needShowFullscreen = !widget->isFullScreen();
+#ifdef WIN32
+                if(widget->isFullScreen())
+                {
+                    needShowFullscreen = false;
+                    needReshowFullscreen = true;
+                }
+#endif
+                LOG_DEBUG("widget is visible, need showFS:%b reshowFS:%b")
+                        << needShowFullscreen << needReshowFullscreen;
 
                 // The window is already visible, so let's allow a mode change to resolve itself
                 // before we go changing the window.
                 LegacyCore_Timer(de2LegacyCore, POST_MODE_CHANGE_WAIT_BEFORE_UPDATE, updateMainWindowLayout);
             }
             else
             {
+                LOG_DEBUG("widget is not visible, setting geometry to ")
+                        << DisplayMode_Current()->width << "x"
+                        << DisplayMode_Current()->height;
                 widget->setGeometry(0, 0, DisplayMode_Current()->width, DisplayMode_Current()->height);
             }
         }
@@ -464,8 +481,17 @@ static void updateMainWindowLayout(void)
 {
     Window* win = Window_Main();
 
+    if(win->needReshowFullscreen)
+    {
+        LOG_DEBUG("Main window re-set to fullscreen mode.");
+        win->needReshowFullscreen = false;
+        win->widget->showNormal();
+        win->widget->showFullScreen();
+    }
+
     if(win->needShowFullscreen)
     {
+        LOG_DEBUG("Main window to fullscreen mode.");
         win->needShowFullscreen = false;
         win->widget->showFullScreen();
     }
@@ -485,6 +511,7 @@ static void updateMainWindowLayout(void)
 
     if(win->needShowNormal)
     {
+        LOG_DEBUG("Main window to normal mode.");
         win->needShowNormal = false;
         win->widget->showNormal();
     }