void gdk_set_allowed_backends ( const gchar* backends )
Sets a list of backends that GDK should try to use.
This can be be useful if your application does not work with certain GDK backends.
By default, GDK tries all included backends.
instructs GDK to try the Wayland backend first, followed by the Quartz backend, and then all others.
GDK_BACKEND environment variable
is set, it determines what backends are tried in what
order, while still respecting the set of allowed backends
that are specified by this function.
The possible backend names are x11, win32, quartz, broadway, wayland. You can also include a * in the list to try all remaining backends.
This call must happen prior to gdk_display_open(),
in order to take effect.