Bug 502105

Summary:	Content behind tabbox blurry and offset while fading away, then snaps correct
Product:	[Plasma] kwin	Reporter:	tempqd <variable_valuables761>
Component:	tabbox	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED FIXED
Severity:	minor	CC:	nate, nyanpasu64
Priority:	VLO
Version First Reported In:	git master
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	Bugged behavior Correct behavior Video of the bug happening on Plasma 6.4.4.

Description tempqd 2025-03-28 02:41:35 UTC

SUMMARY
While alt+tab task switcher/tabbox is fading away, the contents behind it are slightly blurred and offset until it's fully gone, then the content snaps back to normal. This only happens sometimes, oddly.

See attached videos: first is the bugged behavior with two windows in tabbox, and the second is the correct behavior where the only thing I changed was having 3 windows in tabbox instead of two.

OS: openSUSE Krypton (Tumbleweed + KDE git master, Qt 6.8.2, Wayland, amdgpu)

Comment 1 tempqd 2025-03-28 02:42:23 UTC

Created attachment 179805 [details]
Bugged behavior

Comment 2 tempqd 2025-03-28 02:42:43 UTC

Created attachment 179806 [details]
Correct behavior

Comment 3 Nate Graham 2025-03-28 23:14:59 UTC

Are you using a fractional scale factor? If you are, I think there's a plausible way it could be happening, though it'll still be the world's tiniest visual glitch! I'm amazed you were able to notice it at all. I had to pay very close attention in the first screen recording to notice it.

Comment 4 tempqd 2025-03-29 01:25:42 UTC

Hah, indeed tiny but sticks out like a sore thumb to me! I can't rest until every Plasma pixel is perfect :)

I did mean to mention 150% global scale factor, yes!

Comment 5 tempqd 2025-08-31 03:14:41 UTC

I haven't seen this in a while, and I'm not aware of any specific changes that would've fixed it, so I'm just gonna close this for now and reopen if it crops back up.

Comment 6 nyanpasu64 2025-08-31 05:35:06 UTC

Created attachment 184595 [details]
Video of the bug happening on Plasma 6.4.4.

Still happens.

Operating System: Fedora Linux 42
KDE Plasma Version: 6.4.4
KDE Frameworks Version: 6.17.0
Qt Version: 6.9.1
Kernel Version: 6.16.3-200.fc42.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 8 × Intel® Core™ i7-8559U CPU @ 2.70GHz
Memory: 16 GiB of RAM (15.5 GiB usable)
Graphics Processor: Intel® Iris® Plus Graphics 655
Manufacturer: Intel(R) Client Systems
Product Name: NUC8i7BEH
System Version: J72992-303

Comment 7 tempqd 2025-09-03 08:21:45 UTC

I meant that I'm not seeing it in git master, so I expect the fix will appear in the 6.5 release (or maybe a 6.4.x bugfix release?). If you're able to test that and confirm it's been fixed, that would be good.

And if you have steps to consistently reproduce it, I can try it too.

Comment 8 nyanpasu64 2025-09-03 08:31:12 UTC

Unfortunately I don't have specific steps to follow to trigger the issue. Because it's caused by a size/position rounding inconsistency, I think you should test different numbers/sizes of windows for different alt-tab widths, different scale factors (I use 125%), and possibly resolutions (though I don't think it's necessary?).

How do you install KDE software from Git master?

Comment 9 tempqd 2025-09-03 16:54:29 UTC

Yeah I couldn't find a way to consistently reproduce either, no worries.

Devs typically build from git master with kde-builder, but thankfully some distros provide git master builds for us, so I like to test with a VM or live USB of openSUSE Krypton or KDE Neon Testing/Unstable so it doesn't mess with my actual install.

Comment 10 tempqd 2025-11-30 23:30:16 UTC

The fix should be released by now (and I still haven't seen it again in git master), so I'll close, but if anyone experiences it again feel free to reopen.