private void UpdateEventButtonWindow(Gdk.EventButton evnt, Gdk.Window window)
{
// FIXME: GLib.Object.Ref is obsolete because it's low level and shouldn't
// be exposed, but it was in 1.x, and it's not going to go away, so this is OK.
#pragma warning disable 0612
window.Ref();
#pragma warning restore 0612
Marshal.WriteIntPtr(evnt.Handle, IntPtr.Size, window.Handle);
}