Bug 447704

Summary:	Black areas (flashing) on top of windows/desktop
Product:	[Plasma] kwin	Reporter:	yfprojects <yfprojects>
Component:	compositing	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED DUPLICATE
Severity:	normal	CC:	nate
Priority:	NOR
Version:	unspecified
Target Milestone:	---
Platform:	Ubuntu
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:
Attachments:	A screenshot of a newly started Thunderbird window with all other windows minimized that was dragged around and results in a screen with flickering black areas seen in the image.

Description yfprojects 2021-12-30 19:02:41 UTC

Created attachment 144974 [details]
A screenshot of a newly started Thunderbird window with all other windows minimized that was dragged around and results in a screen with flickering black areas seen in the image.

SUMMARY
***
NOTE: If you are reporting a crash, please try to attach a backtrace with debug symbols.
See https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports
***
I can't reproduce this bug reliably (but indeed quiet regularly) and I don't even know whether it is a bug of the kwin compositor.

Sometimes (most often, maybe even only after playing a game through Steam) I can regularly see black areas on my screen when opening new windows. They occur most frequently with Thunderbird an will disappear immediately or flash constantly until I move the focus away from the application or until some time passed. This behaviour persists until restart. When moving the window of an application around the black area gets less as if I were drawing on it with a very low resolution, window-shaped brush. The black areas completely overlay any windows and desktop elements. I attached screenshot which I surprisingly was able to take with Spectacle. They seem related to refreshing the screen. Changing the compositor in the settings or switching to a terminal-only session and back again doesn't help. Both my monitors are affected. CPU, Memory and GPU load is as usual - a little bit of swap but I don't know if that's related. I am using an NVIDIA Graphics Card but hadn't any problems with it yet.

`kwin_x11 --replace` seems to fix it.

Since I don't know how to find out, what causes the issue, I am welcome to follow instruction for collecting more information.

EXPECTED RESULT
No black areas, normal rendering.


SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 
Kubuntu 20.04 (64-Bit)
KDE Plasma Version: 5.18.5
KDE Frameworks Version: 5.68.0
Qt Version: 5.12.8

ADDITIONAL INFORMATION
bug 443951 seems to be a duplicate but I don't have the issue with videos. I didn't have the time to read through the whole thread yet.

Comment 1 yfprojects 2021-12-30 19:07:13 UTC

In case this is fixed in version 5.23 as stated in bug 443951, how can I get the version on my computer?

Comment 2 Nate Graham 2022-01-12 01:10:04 UTC

(In reply to yfprojects from comment #1)
> In case this is fixed in version 5.23 as stated in bug 443951, how can I get
> the version on my computer?
That would depend on your distro, not KDE. Since you're using Ubuntu, you would need to upgrade to the latest non-LTS version (Kubuntu 21.10), which would give you Plasma 5.22. Then you would need to install the Kubuntu Backports PPA to upgrade Plasma 5.22 to 5.23.

*** This bug has been marked as a duplicate of bug 443951 ***