Hi, and thanks for all answers!
Yes, it was just a ugly hack, it has been rewritten..
The problem was that i checked if it was possible to switch to the requested display-mode BEFORE going to fullscreen.
Thats why "device.isDisplayChangeSupported()" allways return "false"..
Now it's working, in Windows, and only if i render directly to a JFrame. If if I render to a JPanel that is added to the JFrames contentPane I only get a grey screen.
Should it not be possible to render to a JPanel in a JFrame?
Looking forward to Mustang so that I can get Linux support up and running.