Well, its no surprise after Ubuntu 12.04 came out, many wanted the old gnome2 like interface back. Some would have tried the gnome classic option in 12.04, or some like me would have tried installing mate – the original fork of gnome2 project.
Chances are there with multiple WMs running, your Mate will have problems applying themes. And when you launch the System->Preferences-Appearance you would get an error message as shown below.
Unable to start the settings manager ‘mate-settings-daemon’.
Without the MATE settings manager running, some preferences may not take effect. This could indicate a problem with DBus, or a non-MATE (e.g. KDE) settings manager may already be active and conflicting with the MATE settings manager
Fix is simple and its explained in these posts http://forums.mate-desktop.org/viewtopic.php?f=6&t=175 and https://github.com/mate-desktop/mate-session-manager/issues/2.
Backup the below files before editing them.
#Replace the contents to the one as shown below.
Name=Mate Settings Daemon
#Replace the exec line as shown below
Exec=/usr/bin/mate-settings-daemon –no-daemon &
Now save these files and reboot. Note: I have not tried to check if other WMs (classic, unity) will work after applying the above method, so try it at your own risk. For now I only needed MATE to be a ‘working’ desktop manager.