sven@samurai:~$ killall kwin
sven@samurai:~$ beryl
**************************************************************
* Beryl system compatiblity check *
**************************************************************
Detected xserver : AIGLX
Checking Display :0 ...
Checking for XComposite extension : passed (v0.3)
Checking for XDamage extension : passed
Checking for RandR extension : passed
Checking for XSync extension : passed
Checking Screen 0 ...
Checking for GLX_SGIX_fbconfig : passed
Checking for GLX_EXT_texture_from_pixmap : passed
Checking for non power of two texture support : passed
Checking maximum texture size : passed (2048x2048)
beryl: Another window manager is already running on screen: 0
beryl: No manageable screens found on display :0