Bug 491427

Summary:	Fractional scaling + Firefox in fullscreen: Maximized YT video shown shrinked when maximized
Product:	[Plasma] kwin	Reporter:	postix <postix>
Component:	wayland-generic	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED UPSTREAM
Severity:	normal
Priority:	NOR
Version First Reported In:	6.1.3
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	Screenshot

Description postix 2024-08-08 10:38:58 UTC

Created attachment 172393 [details]
Screenshot

Not sure whether this is an upstream bug or a kwin bug. :)

STEPS TO REPRODUCE
1. Start Firefox with a new profile (`firefox -p`) on Plasma Wayland
2. Change Plasma's screen scaling to 1.25
3. Open any YT video such as the one for Plasma Akademy
> https://www.youtube.com/watch?v=l61CmpLiCzs
4. Press F11 to make Firefox go into fullscreen mode
5. Press the "Maximize video" button in the lower right corner of the YT video

OBSERVED RESULT
The video is shown shrinked in the upper left corner. The background is white.
When changing the scaling back to 1.0 everything looks fine again.

EXPECTED RESULT
The video is shown full screen independently of the scaling factor. 


SOFTWARE/OS VERSIONS
Operating System: Fedora Linux 40
KDE Plasma Version: 6.1.3
KDE Frameworks Version: 6.4.0
Qt Version: 6.7.2
Kernel Version: 6.9.12-200.fc40.x86_64 (64-bit)
Graphics Platform: Wayland
Firefox 128.0.3 (Wayland) - new profile

Comment 1 postix 2024-08-08 10:44:43 UTC

I think it's an upstream bug. When setting
> widget.wayland.fractional-scale.enabled true
it works, though it introduces tons of other bugs. :')