User switching broken

[Patrick O'Callaghan]

On Fri, 2015-02-20 at 14:05 +0100, Daniel Vrátil wrote:
> On Friday, February 20, 2015 12:29:55 PM Patrick O'Callaghan wrote:
> > I have Plasma-5 and SDDM under F21. Switching sessions to another (test)
> > user, also with Plasma, works. Switching back again gives flashing
> > display garbage and the session is unusable. The problem appears to be
> > with switching to VT1, not to the content of the sessions as such (i.e.
> > if I start the sessions in the reverse order the same problem happens).
> > 
> > I have an Nvidia card with the proprietary driver.
> > 
> > I tried reporting this to bugs.kde.org but there doesn't seem to be a
> > category for SDDM, which I would think is the culprit.
> 
> Could you try restarting KWin after the switch? (switch to a new VT, run 
> DISPLAY=":0" kwin_x11 --replace &)
> 
> Such graphical glitches are usually caused by KWin not dealing with changes 
> properly.

It gave a number of errors but sort of worked, i.e. the glitches went
away and I can now switch back and forth between the two VTs, however:

* Window borders in the first VT (i.e. the starting point) are now
missing.

* The task switcher is present but greyed out, though it still works,
including the multiple desktops.

* The Launcher (K menu) has gone.

The second (test) VT, from which I ran the command you suggested, keeps
logging errors from kwin_core related to desktops on the first VT. I can
do all this again and try to log the output properly if it would help.

poc