Comment 5 for bug 167639

I have found some information on the net: Got it!
Was a gtk theme bug, got the hint here (on bottom of the thread):
http://www.lazarus.freepascal.org/index.php?name=PNphpBB2&file=viewtopic&t=1787
Switching to another gnome theme solved it (broken theme was SmoothGnome btw).

This happened only, when an application is build with gtk1 and this theme is installed, as long as i understood it.