New GDM in Karmic

Since new and fresh karmic koala included GDM 2.28 all gdm themes changed.

Now, you need to run:

gksudo -u gdm dbus-launch gnome-appearance-properties

to modify gdm properties.

I don’t like at all.

If you need/want to disable users list in GDM, you need to run gconf-editor and disable that key.