I'm using TeXstudio 2.5.2 (SVN 3651) on Fedora 18 (Linux 3.7.2-204.fc18.x86_64) installed from the Repos (texstudio2.5.2-1.fc18.x86_64). The program starts maximized and as soon as I de-maximize it for better window arrangement it freezes/crashes my gnome shell and leaves everything unclickable. It also rearranges parts of the screen (a few rectangle shapes seem to be dislodged). Even after killing TexStudio via tty2, gnome shell is still unusable and I'm forced to reboot.
This might be caused by QT in combination with one of my Shell-extensions, "Maximus", but that is only a wild guess and every other programm works just fine with de-maximizeable windows.
Contanct me if you need more in-depth information like syslogs etc.