Gtk.Gesture add method: triggers_context_menu
GTK3 event has method: event.triggers_context_menu()
GTK4 could done this by two ways:
- Gdk.BUTTON_SECONDARY == gesture.button
- get_last_event(seq).triggers_context_menu()
the best way to do this is to add a method directly in Gtk.Gesture
Edited by TAO ZUHONG