Bug 477539

Summary: Snapping a window to maximize on screen 1 when another application on second is maximized creates artifacts on the screen next to it
Product: [Plasma] kwin Reporter: Iason Malkotsis <imalkotsis>
Component: multi-screenAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED FIXED    
Severity: normal CC: fanzhuyifan, nate
Priority: NOR Keywords: qt6
Version First Reported In: 5.27.80   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: video example

Description Iason Malkotsis 2023-11-26 03:52:26 UTC
Created attachment 163489 [details]
video example

SUMMARY

maximizing a window on one screen when another application on a second monitor is already maximized creates render artifacts on second application

STEPS TO REPRODUCE
1. Maximize application on second screen
2. Maximize application on first screen
3. Observe second screen

OBSERVED RESULT
screen 2 has now some artifacts

EXPECTED RESULT
screen 2 should be unaffected

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 5.27.80
KDE Frameworks Version: 5.245.0
Qt Version: 6.6.0
Kernel Version: 6.6.2-zen1-1-zen (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 5800X3D 8-Core Processor
Memory: 31,3 GiB of RAM
Graphics Processor: AMD Radeon RX 6600 XT
Comment 1 Nate Graham 2023-11-27 20:38:19 UTC
Cannot reproduce with two adjacent-but-not-overlapping screens. Are your screens somehow overlapping on the Display & Monitor page in System Settings?
Comment 2 Iason Malkotsis 2023-11-29 07:48:06 UTC
Thanks for taking a look at this.

I checked my settings. No, I don't think they are overlapping.

After testing a bit more, I discovered that it mostly happens with KDE applications like Discover.
Deactivating the Maximize Desktop effect or putting a digital clock widget on the second monitor seems to fix the problem.
You could see if you have either of those things and try with and without them. 

Feel free to ask for more info if you need to.
Comment 3 Nate Graham 2023-11-29 17:56:33 UTC
Still can't reproduce with or without either of those applied.
Comment 4 fanzhuyifan 2023-12-17 07:04:08 UTC
Could you share your display settings when you can produce this? e.g., the output of `kscreen-doctor -o`. Thanks!

I am suspecting that this might be related to the fractional scaling stuff, like https://bugs.kde.org/show_bug.cgi?id=477791
Comment 5 Bug Janitor Service 2024-01-01 03:46:05 UTC
Dear Bug Submitter,

This bug has been in NEEDSINFO status with no change for at least
15 days. Please provide the requested information as soon as
possible and set the bug status as REPORTED. Due to regular bug
tracker maintenance, if the bug is still in NEEDSINFO status with
no change in 30 days the bug will be closed as RESOLVED > WORKSFORME
due to lack of needed information.

For more information about our bug triaging procedures please read the
wiki located here:
https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

If you have already provided the requested information, please
mark the bug as REPORTED so that the KDE team knows that the bug is
ready to be confirmed.

Thank you for helping us make KDE software even better for everyone!
Comment 6 Iason Malkotsis 2024-01-02 08:24:38 UTC
Output: 1 DP-1
        enabled
        connected
        priority 1
        DisplayPort
        Modes:  0:1920x1080@60!  1:1920x1080@240*  2:1920x1080@144  3:1920x1080@120  4:1920x1080@120  5:1920x1080@96  6:1920x1080@72  7:1920x1080@60  8:1920x1080@60  9:1920x1080@60  10:1920x1080@50  11:1920x1080@50  12:1920x1080@48  13:1680x1050@60  14:1600x900@60  15:1280x1024@75  16:1280x1024@60  17:1440x900@60  18:1280x800@60  19:1152x864@75  20:1280x720@60  21:1280x720@60  22:1280x720@50  23:1024x768@75  24:1024x768@60  25:800x600@75  26:800x600@60  27:720x576@50  28:720x480@60  29:720x480@60  30:720x480@60  31:720x480@60  32:640x480@75  33:640x480@60  34:640x480@60  35:640x480@60  36:720x400@70  37:1280x1024@60  38:1024x768@60  39:1280x800@60  40:1920x1080@60  41:1600x900@60  42:1368x768@60  43:1280x720@60 
        Geometry: 0,0 1920x1080
        Scale: 1
        Rotation: 1
        Overscan: 0
        Vrr: Automatic
        RgbRange: unknown
        HDR: incapable
        Wide Color Gamut: incapable
        ICC profile: none
Output: 2 DP-2
        enabled
        connected
        priority 3
        DisplayPort
        Modes:  0:1920x1080@60*!  1:1680x1050@60  2:1400x1050@60  3:1600x900@60  4:1280x1024@75  5:1280x1024@60  6:1440x900@60  7:1280x800@60  8:1152x864@75  9:1280x720@60  10:1024x768@75  11:1024x768@60  12:832x624@75  13:800x600@75  14:800x600@60  15:800x600@56  16:640x480@75  17:640x480@60  18:720x400@70  19:1280x1024@60  20:1024x768@60  21:1280x800@60  22:1920x1080@60  23:1600x900@60  24:1368x768@60  25:1280x720@60 
        Geometry: 1920,0 1920x1080
        Scale: 1
        Rotation: 1
        Overscan: 0
        Vrr: incapable
        RgbRange: unknown
        HDR: incapable
        Wide Color Gamut: incapable
        ICC profile: none
Comment 7 Iason Malkotsis 2024-01-02 08:31:11 UTC
Retested using the latest KDE plasma 6.0 beta 2 and it seems that this is no longer an issue