Comment 15 for bug 818201

I have a similar issue with regards to guest sessions. I've tried to manually set the dmrc in /usr/sbin/guest-account, but that doesn't work. I suppose there is a reason why those lines are commented. I've also tried adding it to /etc/guest-session/skel/.dmrc, but that also doesn't work.

When I say "doesn't work", I mean that after login, $/home/.dmrc uses Session=ubuntu no matter what I do. This is bad, because some users have setups that are capable of running Unity, but get a much better performance with Unity 2D. Of course, you might want to let the guests use the same shell as you're using yourself.