The ::key-press-event signal is emitted when a key is pressed. The signal
emission will reoccur at the key-repeat rate when the key is kept pressed.
To receive this signal, the gdk.Window associated to the widget needs
to enable the GDK_KEY_PRESS_MASK mask.
This signal will be sent to the grab widget if there is one.
TRUE to stop other handlers from being invoked for the event.
FALSE to propagate the event further.