Thanx Paul, I really appreciate your help + code samples!

I already got wmctrl installed and running it does everything I need so far! 8)

... and yes the WM is indeed metacity, the default installed with gnome. (Actually I really do not care much, as long as I have the least possible administration tasks setting up my ubuntu box, which may distract me from hacking ... )

Anyway X11::GUITest does muuuuch more than wmctrl, e.g sending keystrokes to the app, simulating a typing user - excellent!

That's something I have on my todo list for a long time now, so muchas gracias again!!! 8)