Protect hildon_window_event_filter() with gdk_threads_enter()
Protect hildon_window_event_filter() with gdk_threads_enter()

Fixes: NB#142072 (Menu becomes blank after multiple tapping)

Cordia/libhildon,Cordia/libhildon,android-808/libhildon,Cordia/libhildon,android-808/libhildon,android-808/libhildon