Comment 17 for bug 137745

Also wanted to add support for rettichschnidi's suggestion. If Hardy Heron is pushed out the door with Desktop Effects enabled and there is a known limitation of X that you can't run Desktop Effects as a second user when "Switching Users," it makes no sense to leave it at a cryptic error message.

Users that don't know any better will just get frustrated and have a degraded user experience if they run into this problem with only an error message of "Sorry, couldn't do that" without some explanation of why. Just saying that "2 users can't use desktop effects at the same time" would be enough to allow people an idea of what is going on, rather than just forcing them to run into the brick wall of nothing but "it won't work."