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