Use QApplicationPrivate::getHWNDForWidget for getting
the HWND for Widgets. The Menubar needs refactoring,
but the API for native Menubars is not in place yet,
so fix it temporarily.
Change-Id: I090cca99d19aa881c2f41b54005a65f3ae67ae68
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>