Created attachment 113457 [details]
qdbus org.kde.KWin /KWin org.kde.KWin.supportInformation

Since upgrading to Plasma 5.13.0 from 5.12.5, I've observed a regression on my VirtualBox-based VM that runs on my work notebook (host is Windows 10). To reproduce:

1. Start out with a Konsole window only. (That's usually all that I have open.) At this point, everything works as far as I can see.

2. Open some other application. I tried Firefox and Filelight, both by running them either from the Konsole or from KRunner.

3. The other application window opens. At this point, weird behavior ensues.  Clicking into the other app causes Konsole to come back to the front. Clicking on the panel does nothing. Using the mouse wheel (on either app) cycles between the open windows, bringing them to the front in turns. Left clicks into the Konsole window get ignored, but right clicks work and bring up its context menu. 

4. Run "kwin_x11 --replace &" from the terminal. This is the only thing so far that restores normal behavior for me, except that the app switcher in the panel continues to not work (it reacts to hover events by highlighting the hovered entry, but clicking on an entry does not do anything).

5. Change the active window with Alt-Tab. The weird behavior from step 3 re-emerges.

Note that this bug only affects mouse events. Keyboard events work fine in all windows. Global shortcuts are not affected, either.

I checked the pacman.log to see if any other updates installed at the same time may be causing the troubles, but found nothing that would be related to the behavior observed.