Comment # 7 on bug 980521 from Martin Szulecki

So, when "gdm-x-session" runs "/etc/gdm/Xsession" is called.
Due to SuSE specific patches that also runs "/etc/X11/xdm/Xsession" which runs
"/etc/X11/xdm/sys.xsession".

However, when "gdm-x-session" is run, it spawns a new user session bus already
if one was not yet started for the user.

Thus DBUS_SESSION_BUS_ADDRESS will be populated with a valid session.

Once within the "sys.xsession" script, it will destroy the valid session with
the line "test -n "$dpid" || unset DBUS_SESSION_BUS_ADDRESS", which causes a
new dbus user session to be created by the script and causes havok later on for
the dbus user session pingpong of GVFS and other GNOME related components.

As far as I understand this really messy startup procedure... I think it should
not unset a valid DBUS_SESSION_BUS_ADDRESS and therefore not start a new
dbus-daemon in the "gdm" case to fix proper GNOME session startup for "gdm".