Bug 506258

Summary:	Plasma screen edge flickering
Product:	[Plasma] kwin	Reporter:	dpeter99 <dpeter99>
Component:	compositing	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	CONFIRMED ---
Severity:	normal	CC:	nate, realkpavel
Priority:	NOR	Keywords:	multiscreen
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	My display setup

Description dpeter99 2025-06-27 09:29:07 UTC

SUMMARY
Constant high frequency flickering on monitor edge.

STEPS TO REPRODUCE
1. Open a kitty terminal
2. Set it full screen

OBSERVED RESULT
The right edge of the fullscreen window flickers.

EXPECTED RESULT
No flickering

SOFTWARE/OS VERSIONS
Operating System: Fedora Linux 42
KDE Plasma Version: 6.4.0
KDE Frameworks Version: 6.15.0
Qt Version: 6.9.1
Kernel Version: 6.15.3-200.fc42.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 5800X 8-Core Processor
Memory: 32 GiB of RAM (31.3 GiB usable)
Graphics Processor: AMD Radeon Graphics
Manufacturer: Micro-Star International Co., Ltd.
Product Name: MS-7C91
System Version: 2.0

ADDITIONAL INFORMATION
I'm running a bootc distro. 
https://github.com/dpeter99/glados-image
https://quay.io/repository/dpeter99/glados-bootc-image?tab=tags
tag: fedora42-nvidia-2025-06-26

The apps that seam to have this are all started from a distrobox container.

Comment 1 dpeter99 2025-06-27 09:41:37 UTC

Here is a video of it:
https://youtube.com/shorts/R0fs4p7KipM

Comment 2 Kat Pavlu 2025-06-27 15:30:01 UTC

I suspect this might be a fractional scaling issue. Can you say what display scale you are using?

Comment 3 dpeter99 2025-07-02 10:30:50 UTC

Created attachment 182859 [details]
My display setup

Comment 4 dpeter99 2025-07-02 12:57:18 UTC

additional video:
The flickering line stays even after minimizing the kitty window
https://youtube.com/shorts/wlOsGvt2zTc?feature=share

Comment 5 Kat Pavlu 2025-07-02 15:40:57 UTC

I cannot reproduce the exact behavior with kitty, but I can get a similar flicker with a 3440x1440p monitor at 1.15 scale on the bottom edge while using Remmina (can't get it to happen with kitty).

Changing the display scale, even slightly, fixes the flicker for me. Can you test this workaround? Set the scale to 134% instead of 135