Gdk::Window: Remove add/remove_filter().
Gdk::Window: Remove add/remove_filter().

Because they were removed from GTK+ 4:
https://gitlab.gnome.org/GNOME/gtk/commit/89f6b8751e79ba597fcbd8292df377fa98a7319f

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