Every time i press f11 to make my minecraft fullscreen, the gnome panels are ALWAYS annoying me up n' down. How to get rid of 'em? Just clicking again on minecraft doesn't help :(. (Ubuntu 10.10)
Have you tried disabling "desktop effects"? This usually works for me if I have panels showing over fullscreen applications.
This is under:
System > Preferences > Appearance > Visual Effects > None
A simpler solution than turning off desktop effects is to turn on "Autohide" in the panel's properties. You can reach this by right-clicking the panel.
It's not a perfect solution, but you get the full screen.