Bug#836932: login to blank screen after upgrade to 0.9

[Christian Pernegger <pernegger@gmail.com>]

Hello again!

> So the problem is neither xrdp nor the X server.

I'll concede that testing might be horribly broken at the moment,
especially in the GTK3 department. But considering MATE, xfce4 and
LXDE all work for local logins, but under xrdp 0.9 MATE and LXDE give
an empty background and xrdp4 only works with some clients(!), xrdp
has to be at least a part of the problem.
My main gripe is that it doesn't behave very consistently. Sometimes
sesman starts, sometimes it doesn't. On a fresh boot (w/ sesman
running) I always get the behaviour above, but there were times (after
trying different users, clients, desktop environments, local/xrdp
logins), when it suddenly, magically started to work -- until the next
sleep or reboot. Even then, connecting to a running session from
another machine would not work. 0.9 also refuses to launch VNC
sessions or connect to existing ones. Too many different problems to
pin down the cause.

> Anything else special about this setup?

No. Plain vanilla stretch install, at least it was supposed to be.

>> * Neither the VNC options nor "console" work at all anymore.
>
> Well, did you install the relevant packages, like a VNC server?

The 0.6 setup was of course VNC based and I didn't uninstall them. The
x11vnc configured to attach to the local X server's still running
strong, xrdp just doesn't like it, it just disconnects after a
successful login (lightdm login, not xrdp).

>> * Going back to 0.6.1 doesn't help.
>
> Did you make sure to also recreate the old config files?

No, but I didn't have to do anything special to get basic operation
out of 0.6 either. FWIW, I've gotten 0.6 to work again. Looks like it
has to be xfce for now (I'd only tried MATE before), but I can live
with that.

> Another thing: What PAM modules do you have enabled in common-session?
> Anything non-default?

No, bog standard.

I'm sticking with 0.6 for now, but if you have any ideas or a version
with much better logging, I'm perfectly willing to test it one weekend
or other.

Cheers,
C.