Bug 1145448 - Avoid painting native frame on fullscreen window when activate/inactivate. r=jimm

--HG--
extra : source : 2142c3433366414d98da4008756932a8765c8a08

widget/windows/nsWindow.cpp

@@ -4686,7 +4686,9 @@ nsWindow::ProcessMessage(UINT msg, WPARAM& wParam, LPARAM& lParam,
         break;
 
       // let the dwm handle nc painting on glass
-      if(nsUXThemeData::CheckForCompositor())
+      // Never allow native painting if we are on fullscreen
+      if(mSizeMode != nsSizeMode_Fullscreen &&
+         nsUXThemeData::CheckForCompositor())
         break;
 
       if (wParam == TRUE) {