Bug 505225

Summary:	Firefox context menu glitches when clicked at the very top with fractional scaling on Wayland
Product:	[Plasma] kwin	Reporter:	iodreamify
Component:	general	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	CONFIRMED ---
Severity:	normal	CC:	javispedro+kde, kdedev, madness742, nate
Priority:	NOR	Keywords:	wayland-only
Version First Reported In:	6.3.5
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:
Attachments:	video

Description iodreamify 2025-06-05 02:19:58 UTC

Created attachment 182041 [details]
video

SUMMARY
With fractional scaling 1.25x if i right click near the very top of Firefox's maximized window i get a context menu which starts glitching out flashing semi-transparently as the mouse is moving over the elements. I can still click on the elements but there are graphical glitches. If i move my mouse even a little bit down context menu works correctly again. I've recorded a short demo. 

This does not happen without fractional scaling. It also doesn't happen on X11. 

Probably related links: 
https://bugs.kde.org/show_bug.cgi?id=466092
https://discuss.kde.org/t/weird-firefox-context-menu-issue-on-kde-wayland/16033

STEPS TO REPRODUCE
1. Use fractional scaling like 1.25x on Wayland
2. Maximize Firefox's window
3. Right click near the very top of an open tab
4. Move mouse over the elements

OBSERVED RESULT
Context menu starts rapidly warping in and out as if it's opening and closing  

EXPECTED RESULT
Context menu works reliably

ADDITIONAL INFORMATION
Operating System: Arch Linux 
KDE Plasma Version: 6.3.5
KDE Frameworks Version: 6.14.0
Qt Version: 6.9.0
Kernel Version: 6.14.9-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 12 × AMD Ryzen 5 7535HS with Radeon Graphics
Graphics Processor 1: NVIDIA GeForce RTX 4050 Laptop GPU
Graphics Processor 2: AMD Radeon 660M

Comment 1 Nate Graham 2025-06-05 15:07:57 UTC

Cannot reproduce on current git master with Firefox 139 and 175% scale.

Comment 2 iodreamify 2025-06-05 15:24:40 UTC

Some additional info: 
Firefox 139.
Also tested with a clean profile. 
Also present with 175% scaling for me.

Comment 3 TraceyC 2025-06-05 19:02:07 UTC

I can reproduce on current git master with Firefox 139 and 125% scale.
It doesn't happen with 100%

This is on a laptop display with 1920 x 1080 resolution

Operating System: Solus 4.7
KDE Plasma Version: 6.4.80
KDE Frameworks Version: 6.15.0
Qt Version: 6.8.3
Kernel Version: 6.14.6-319.current (64-bit)
Graphics Platform: Wayland
Processors: 8 × AMD Ryzen 7 3700U with Radeon Vega Mobile Gfx
Memory: 20 GiB of RAM (17.5 GiB usable)
Graphics Processor: AMD Radeon Vega 10 Graphics
Manufacturer: LENOVO
Product Name: 81SS
System Version: Lenovo IdeaPad FLEX-14API

Comment 4 Javier 2025-06-22 13:33:56 UTC

Personally I can reproduce it in openSUSE Tumbleweed  with Fx 139 and kwin 6.4.0  , no need for fractional scaling.
Even 200% shows the issue. I can consistently reproduce the issue with any scaling value other than 100%. 
It is also not a recent regression. I also had the same issue for the entire kwin 6.3.x.