Propagate a key press or release event to the focus widget and
up the focus container chain until a widget handles
This is normally called by the default ::key_press_event and
::key_release_event handlers for toplevel windows,
however in some cases it may be useful to call this directly when
overriding the standard key handling for a toplevel window.
TRUE if a widget in the focus chain handled the event.
Derived by RGtkGen from GTK+ documentation