Comment 1 for bug 1187969

Well, that's a simpler description and the detail's in the comment anyway, but I had no way of knowing if the GUI approach might be touching anything in the 'alternatives' system or thereabouts different from direct apt manipulation.

Let me know if there's anything I can do to assist in solving, maybe I can see if this is reproducible from liveUSB where it wouldn't be hard to write a stick and get back to the "Xorg radeon driver actually works fine until you try something else" state.