Comment 7 for bug 1450137

I did a few tests:

On the first reboot after installing qtdeclarative from the Wily PPA on Vivid, I probably got lucky and managed to plug/unplug the external monitor 4 times before the first crash (nvidia-340's xrandr also stopped detecting changes for the next 2 topology changes at that point, although that's nothing new).

On subsequent reboots I'm getting Plasma/Kwin/Konsole crashes on almost every screen change.
Some changes in behaviour that I noticed:

1. Dr. Konqi is started for kwin crashes, but no window appears (no mention of it in xlsclients either).
2. Dr. Konqi is not started for plasmashell crashes (crashes on almost every screen change).
3. Dr. Konqi is not started for Konsole crashes (crashes on every screen change).
4. krunner does not crash on screen change - it crashes instead when called with Alt+F2, with Dr. Konqi appearing. It doesn't allow me to report krunner crashes by the way, but that's another bug. The backtrace (which I'm attaching) is different this time, there's no physicalSize() in it. Luckily it's restarted right after usually, so there's a way to recover manually.
5. System Settings 5 also usually crashes around screen changes; that's caught by apport however, which gives me zero information.
6. Usually after a crash, the Plasma panel flickers, with only the spacer being displayed when not flickering, and can't be clicked. Disabling composition with the shortcut works around this.

All in all, I'd say the behaviour has improved a bit, as regards the frequency of crashes; however, losing Dr. Konqi is mildly disappointing.

I have to apologise here for jumping on this patch without having tested it myself first. I'll try pre-attaching gdb to kwin/plasmashell/konsole to get backtraces out of them, and a Fedora install in the next days to see if the crashes are really fixed, at least on my machine, and report back.