Binary package hint: gdm-guest-session
When in a LightDM session (Natty or Oneiric) gdm-guest-session does not work:
~$ guest-session --no-lock
Error org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.DisplayManager was not provided by any .service files
~$
The fix in bug 795723 was not sufficient. Maybe something like this is needed in lightdm:
http://bazaar.launchpad.net/~ubuntu-desktop/gdm/ubuntu/view/head:/debian/patches/ubuntu_guest_session.patch
As a side note, gdm-guest-session does not work in Oneiric with gdm 3 (built from my latest merge proposal) either, but in that case there is no error message. The only thing printed is something like:
method return sender=:1.8 -> dest=:1.61 reply_serial=2
object path "/org/gnome/DisplayManager/Display2"
but that's printed also in Natty with gdm 2 where it works.
I am able to fire off a guest session, and I do get to the guest display. But, when I try to get back to my base session, everything unravels -- I *can* get back to the base session, but cannot get to the guest again; eventually, the system is unusable (if I keep trying), and I cannot anymore use either guest or base. Will retry later, and collect data.