Version: (using KDE 4.4.3) OS: Linux Installed from: Ubuntu Packages I have a netbook using intel drivers. In KDE 4.4, if I plug an external monitor and set it not to mirror the netbook's LCD (for example, placing on the right side of the netbook), X crashes when composite is on. I have to manually suspend it in order to avoid the crash. Composite should be suspended (and not allowed to be enabled) when an external monitor is active. I don't know if this is a limitation of intel graphics or something general, but in GNOME (at least on ubuntu), when an external monitor is activated, desktop effects are disabled and can't be enabled until a single monitor is set again. See https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/559039
Just at the moment I'm enjoying compositing on two screens. So yeah that sounds like a driver issue and it should never ever crash the X server (a client can't crash the server). So automatically suspending compositing would be the wrong thing to do as it just circumvents driver bugs for some users, but also suspends it for all those users with working drivers. Sorry we cannot do anything about it, you should report the issue to the driver developers.