One possible answer to my own question is, that AMD's ATI Catalyst driver disables the Xorg RandR extension and enables it's own RandR extention:
from /var/log/Xorg.0.log: [...] [ 68.714] (II) fglrx(0): RandR 1.2 support is enabled! [ 68.714] (II) fglrx(0): RandR 1.2 rotation support is enabled! [...] [ 69.541] (II) fglrx(0): Disabling in-server RandR and enabling in-driver RandR 1.2. [ 69.975] (--) RandR disabled [...] [ 69.975] (II) Initializing built-in extension RANDR [...] [ 92.101] (II) fglrx(0): Restoring Recent Mode via PCS is not supported in RANDR 1.2 capable environments Any idea, how to change this configuration? -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/883319 Title: xrandr --scale restricts area in which mouse moves To manage notifications about this bug go to: https://bugs.launchpad.net/xorg-server/+bug/883319/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs