I upgraded to Quantal recently, and Minecraft seems to not want to run in fullscreen. When I go to fullscreen it, the screen will go black for a second, as if it was about to go fullscreen normally, but then it just restores back into its window. So far I have tried:
using different JREs (I've tried openjdk 6 and 7, as well as oracle7). Oracle's jre wouldn't even run Minecraft (I just got a black screen after logging in)
switching graphics drivers (tried nvidia-current, nvidia-current-updates, and xserver-xorg-video-nouveau)
updating minecraft bin files
updating lwjgl libraries separately from the lwjgl site
None of this seemed to work at all.
I am running Minecraft with the command
java -Xmx1024M -Xms512M -cp minecraft.jar net.minecraft.LauncherFrame
Graphics card is GeForce 9500 GS/PCIe/SSE2.
Everything was working fine a few days ago when I was on 12.04.