Forwarded from Debian BTS https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=842333
if I ssh (no -X) to a box running lxdm and try to run DISPLAY=:0 xeyes
I get an error because I don't have the rights to the display.
Now, if I log directly into lxdm on that box, then logout, and retry the
ssh then DISPLAY=:0 xeyes from remote, that works : the eyes appear on
the lxdm login screen!
Restarting lxdm fixes the issue.
Perhaps the same as https://bugzilla.redhat.com/show_bug.cgi?id=1269917
If you set "reset=1" to data/lxdm.conf.in (i.e. /etc/lxdm/lxdm.conf), does it help?
Well, I'm not an original bug reporter and don't use lxdm, it will take time to check, although mentioned by you bug report was never fixed, and perhaps reset will eliminate the issue, but that's not fix but a workaround.
reset=1 option is not an workaround.
But if someone can login the system, X server likely can't be any luck.
Anyway, while you are finding the solution, I think enforce reset=1 will be a workaround, as it fixes the issue. Thank you.