Bug 455415 - Dragging the Firefox window between screens with mixed DPI makes the window flicker on releasing it
Summary: Dragging the Firefox window between screens with mixed DPI makes the window f...
Status: RESOLVED UPSTREAM
Alias: None
Product: kwin
Classification: Plasma
Component: effects-overview (show other bugs)
Version: 5.27.4
Platform: openSUSE Linux
: NOR normal
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords: multiscreen, wayland
Depends on:
Blocks:
 
Reported: 2022-06-16 14:26 UTC by postix
Modified: 2024-06-09 16:18 UTC (History)
3 users (show)

See Also:
Latest Commit:
Version Fixed In:
Sentry Crash Report:

Attachments
Screen recording (1.23 MB, video/x-matroska)
2022-06-16 14:26 UTC, postix 		Details
kWin Support Info (6.83 KB, text/plain)
2022-06-16 14:27 UTC, postix 		Details
Screen recording: Moving Firefox, OBS and Kate in normal mode (3.06 MB, video/x-matroska)
2022-06-17 09:25 UTC, postix 		Details
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Description postix 2022-06-16 14:26:54 UTC 
Created attachment 149802 [details]
Screen recording

SUMMARY

Moving the Firefox window between screens by drag and drop makes the Firefox window flicker annoyingly. 

STEPS TO REPRODUCE
Please see the screen recording.


SOFTWARE/OS VERSIONS
Operating System: openSUSE Tumbleweed 20220613
KDE Plasma Version: 5.25.0
KDE Frameworks Version: 5.94.0
Qt Version: 5.15.2
Kernel Version: 5.18.2-1-default (64-bit)
Graphics Platform: Wayland
Graphics Processor: AMD Radeon RX 580 Series
Comment 1 postix 2022-06-16 14:27:08 UTC 
Created attachment 149803 [details]
kWin Support Info
Comment 2 Vlad Zahorodnii 2022-06-17 06:56:40 UTC 
You have a mixed dpi setup and firefox moves between outputs with different scale factors. Are there visible visual changes when firefox moves between outputs in normal mode, i.e. when not running overview? If so, this needs to be fixed in firefox. Also, does it happen with other apps?
Comment 3 postix 2022-06-17 09:25:23 UTC 
Created attachment 149847 [details]
Screen recording: Moving Firefox, OBS and Kate in normal mode

(In reply to Vlad Zahorodnii from comment #2)
> You have a mixed dpi setup and firefox moves between outputs with different
> scale factors. Are there visible visual changes when firefox moves between
> outputs in normal mode, i.e. when not running overview? If so, this needs to
> be fixed in firefox. Also, does it happen with other apps?

Yes, there are visual issues when moving Firefox and OBS between the mixed DPI screens, all other apps I use/tested were fine though. (Which does not mean that there are more). Please see the screen recording.

I do not however see this issue with OBS in the overview effect when moving its window.
Comment 4 postix 2022-07-14 13:45:48 UTC 
Interestingly I made the exact same observation for this issue, which I made in [1]

left    A: 1920x1080 screen 
right B: 3840x2160 screen (primary) 
on Plasma 5.25.2 Wayland

Scaling of A / B:
100 / 200: issue appears
125 / 200: fine
150 / 200: fine
175 / 200: fine
200 / 200: fine
225 / 200: issue appears
250 / 200: issue appears
275 / 200: issue appears
300 / 200: issue appears

[1] https://bugs.kde.org/show_bug.cgi?id=432264#c27
Comment 5 postix 2023-04-10 15:48:03 UTC 
Still flickers, yet it looks little bit different and only occurs when dragging from the 4k@200% (primary, right) to the 2k@100% screen.
Comment 6 Zamundaaa 2024-06-09 16:18:10 UTC 
This is a bug in Firefox, it's not synchronizing rendering to Wayland surface state changes, which sometimes means the window gets 2x larger before becoming the correct size again. Please report it to Mozilla