Open new session with same user (in GDM)

[Alois Mahdal <alois.mahdal.1-ndmail@zxcvb.cz>]

Hello to all!

How do I create two same-user sessions from GDM?

Say I'm logged in in Xfce (which I normally use, therefore have
many windows / apps open) and want to quickly report a bug. But
before I do that, I want to check if the same happens in GNOME.

xfswitch-plugin ("User switching" in Panel item menu), gets me
to the GDM, but even if I choose my username and "Gnome classic"
session, typing my password only brings me to the old Xfce4
session (i.e. the "session" option in GDM is ignored).

Thanks,
aL.

P.S.: While typing this, I realized that 90% of these cases can
be solved by creating a new temporary user, which is way more
correct way of bug reporting.  However, in some cases (hard to
reproduce bugs, missing privileges to create user...) that might
not be the solution.

-- 
Alois Mahdal