Bug 449098

Summary: Unplugging HDMI, windows move to DP screen and are rendered at lower resolution / blurry + potential graphical artifacts on mouse hover
Product: [Plasma] kwin Reporter: postix <postix>
Component: wayland-genericAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED UPSTREAM    
Severity: normal CC: nate, postix
Priority: NOR Keywords: wayland-only
Version First Reported In: 5.23.90   
Target Milestone: ---   
Platform: Other   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: KWin support information (DP + HDMI attached)
Screenshot: Initial situation (DP + HDMI)
Screenshot: Situation after unpluggin the HDMI cable
Screenshot: Hovering the mouse over Dolphin's window
Screenshot: Hovering the mouse over Konsole's window
KWin support information (DP only, HDMI detached)

Description postix 2022-01-24 20:54:10 UTC
Created attachment 145884 [details]
KWin support information (DP + HDMI attached)

SUMMARY

Left: 4k@200% DP monitor (primary)
Right: FullHD@100% HDMI monitor with Konsole, Systemsettings and Dolphin window

STEPS TO REPRODUCE
1. Unplug the HDMI cable

OBSERVED RESULT
All windows from the right monitor move to the left and in the same stacking order as expected:
Top to bottom: Systemsettings, Dolphin, Konsole

However:
* Konsole and Dolphin first appeared blurry and the SystemSettings very pixelated. 
* When hovering the mouse over Dolphin's window, it started to show black bars, then white bars, but it became clear again.
* When hovering the mouse over the Konsole's window, it started showing the background image, and later while still hovering, part of its controls again.

SOFTWARE/OS VERSIONS
Operating System: KDE neon Testing Edition
KDE Plasma Version: 5.23.90
KDE Frameworks Version: 5.91.0
Qt Version: 5.15.3
Kernel Version: 5.13.0-27-generic (64-bit)
Graphics Platform: Wayland
Graphics Processor: Radeon RX 580 Series
Comment 1 postix 2022-01-24 20:56:06 UTC
Created attachment 145885 [details]
Screenshot: Initial situation (DP + HDMI)
Comment 2 postix 2022-01-24 20:56:38 UTC
Created attachment 145886 [details]
Screenshot: Situation after unpluggin the HDMI cable
Comment 3 postix 2022-01-24 20:57:28 UTC
Created attachment 145887 [details]
Screenshot: Hovering the mouse over Dolphin's window
Comment 4 postix 2022-01-24 20:57:58 UTC
Created attachment 145888 [details]
Screenshot: Hovering the mouse over Konsole's window
Comment 5 postix 2022-01-24 20:58:51 UTC
Created attachment 145889 [details]
KWin support information (DP only, HDMI detached)
Comment 6 Vlad Zahorodnii 2022-01-25 08:37:15 UTC
If both outputs have the scale scale factor, can you reproduce this issue? This sounds like the issue where desktop context menu is partially drawn because Qt handles poorly outputs with different scale factors.
Comment 7 postix 2022-01-25 12:56:57 UTC
(In reply to Vlad Zahorodnii from comment #6)
> If both outputs have the scale scale factor, can you reproduce this issue?

If they have the same scale factor, like 100%, I cannot reproduce it.
Comment 8 Vlad Zahorodnii 2022-01-25 12:59:03 UTC
This is a Qt bug.
Comment 9 postix 2022-01-25 13:36:04 UTC
(In reply to Vlad Zahorodnii from comment #8)
> This is a Qt bug.

Do you have the corresponding bug report ID by chance to follow the issue?