gboolean gtk_window_is_fullscreen ( GtkWindow* window )
Retrieves the current fullscreen state of
Note that since fullscreening is ultimately handled by the window
manager and happens asynchronously to an application request, you
shouldn’t assume the return value of this function changing
immediately (or at all), as an effect of calling
If the window isn’t yet mapped, the value returned will whether the initial requested state is fullscreen.