As with Wayland, the X11 backend may not be available at run-time, so types defined in it can't be used
For GTK, the current implementation assumes X11 is the only window option. Introduce runtime checks to manage Wayland too. Signed-off-by: Pierluigi Passaro <pierluigi.p@variscite.com> Closes https://github.com/wxWidgets/wxWidgets/pull/2257