Hi jose,
I also compiled the source code you showed me in the link
http://library.gnome.org/devel/gdk/stable/gdk-Windows.html#gdk-Windows.description
and also got the warning that compositing was not possible, but the example looks like to do where is made for, even when I comment out the line with " gdk_window_set_composited (event->window, TRUE); ". Does that mean that if I create the widget using gtk instead of gtkmm, I have a better chance????