I'm in Gnome but if I logout I can get to a menu where I can choose KDE as well as other window managers. The problem is I have a program that's running inside Gnome and I don't want to stop it. Is there some way I can get into KDE without having to stop this program?
Does this program have a window? or can it just run in the background?
If it's just running on a terminal, one simple thing you can use screen to keep the process running.
Also look at the the nohup command
I once used the gdm.conf to do so. And as following link mentioned, this not gonna work as before.
Ubuntu 10.04 (Lucid)
The steps are the same as 9.10 -- GDM 2.30 and ConsoleKit 0.4.1 do not have native Multiseat support, nor will GDM lauch two static X sessions like it used to in 2.20. If you do not want to use KDM, Multiseat branches exist for GDM and ConsoleKit; they are described here:
You can check more details on page to use kdm to get this done: https://help.ubuntu.com/community/MultiseatX