Gtk::Widget: Remove property_events()
Gtk::Widget: Remove property_events()

Because it was removed from the GTK+ API:
https://git.gnome.org/browse/gtk+/commit/?id=a72404dd5ab1874ac3d601cd94e0fa7184873851

GNOME/gtkmm,GNOME/gtkmm,GNOME/gtkmm,GNOME/gtkmm