Summary: Hi, first of all I added this bug for kwin due to the fact that I think it is releated to a strange kwin behaviour when stopping compositing for games, it happens only when I open games or even steam, however it is not always predictable. 
If I went wrong, I would kindly ask to change the product/component. Thanks.

Additional information: 
- Manjaro Linux updated to the latest version on 11/05/18
- Nvidia 396 Drivers
- Kernel 4.14

Steps to reproduce:

- Open Steam/Games, happens also with non-fullscreened games.
- Alt-Tab, or just move the mouse out the game

It happens sometimes. Like 40/50% of chance when you open an OpenGL Game. 

Actual result: The plasma shell becames unusuable, the windows tabs on the taskbar doesn't update, the clock and other components too, they are like in a "freezed" state like before I opened that game, If I click however it seem to minimize/maximize windows but the content list does not update, if I close some other window except the game, it remains the same. Another strange thing is that for fullscreened games the compositing does not always turn off, in fact there is a noticeable input delay (Don't always comes with the "freezed state" plasma shell.

Workaround: Close the game fixes it every time, or killing the kwin_x11 process or sometimes even the plasmashell process. Also sometimes CTRL + MAIUSC + F12 fixes the problem, other times not *

*There is even a strange thing, always "Sometimes" when even after I close the game, pressing CTRL+MAIUSC+F12 which disables the compositor, turns back plasma shell to the "freezed" state, but the OLD one. Even if I open other games after. And doing that command once again it always SOMETIMES fix the "problem" and everything goes back into normal when the compositor is either on or off, I made a video for that. It is harder to explain and debug than the way it comes out...

Expected result: Even with compositing off, the plasma shell should be usuable, the window list in the taskbar usuable. CTRL+MAIUSC+F12 should just disable the compositor, and fullscreen games should turn of the compositor without mess.


I was not able to to extract some logs due to the fact it does not always happen, and I don't know the tools to use (gdb?) maybe they are wrong, I would kindly ask the ones I have to use in order to (or at least try) to debug it correctly.

They are a lot hard to debug due to the fact they are not predictable, however I will do my best.

* In the video I show after an hour I played that game, pressing CTRL+MAIUSC+F12 for turning off the compositing, even if I don't even alt-tabbed once, made the usual shell freeze problem, and a second time renabling the compositing "fixes" the problem, I don't know if it always works for fixing