Bug 491153

Summary: When using two monitors, maximized XWayland applications do not reach the top of the screen for clicking
Product: [Plasma] kwin Reporter: Owen <owen>
Component: xwaylandAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED DUPLICATE    
Severity: minor CC: fanzhuyifan
Priority: NOR    
Version First Reported In: unspecified   
Target Milestone: ---   
Platform: Fedora RPMs   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: Video of the issue

Description Owen 2024-08-02 05:56:25 UTC
Created attachment 172200 [details]
Video of the issue

SUMMARY
Some applications cannot be clicked at the very top of the screen when maximized and using two monitors.

STEPS TO REPRODUCE
1. Plug in a second monitor
2. Maximize an XWayland application on the primary monitor (in the video example, I use PrusaSlicer)
3. Click on the very top of the screen

OBSERVED RESULT
Clicking on the very top of the maximized app will instead click on what is behind it, like the desktop or another app. As well, the close, maximize, and minimize buttons do not reach to the top pixel when they normally do.

EXPECTED RESULT
Maximized applications should reach the top edge of the screen (which they do visually, just not for user interaction)

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora 40 
KDE Plasma Version: 6.1.3
KDE Frameworks Version: 6.4.0
Qt Version: 6.7.2

ADDITIONAL INFORMATION
Not sure if it happens on all resolutions. For me, my primary monitor (on which the issue occurs) is 2560x1600 and the secondary monitor (on which the issue does not occur) is 1920x1080. The issue also does not occur if the second monitor is disconnected. See video for a demonstration of the issue.

This issue is weirdly specific so I imagine there may be some issue replicating it - let me know if there's any more information I can provide to help. I have done some experimentation and narrowed it down to only apps running through XWayland that do this - all other apps I tested worked fine and I didn't find any XWayland apps that did not have this issue.
Comment 1 fanzhuyifan 2024-08-02 17:11:49 UTC
What is the output of `kscreen-doctor -o`? Are you using fractional scaling?
Comment 2 Owen 2024-08-02 18:43:54 UTC
(In reply to fanzhuyifan from comment #1)
> What is the output of `kscreen-doctor -o`? Are you using fractional scaling?

Yeah, the main monitor is on 150% scale. Here's the output:

Output: 1 eDP-2
        enabled
        connected
        priority 1
        Panel
        Modes:  0:2560x1600@165*!  1:2560x1600@60  2:1920x1200@165  3:1920x1080@165  4:1600x1200@165  5:1680x1050@165  6:1280x1024@165  7:1440x900@165  8:1280x800@165  9:1280x720@165  10:1024x768@165  11:800x600@165  12:640x480@165  13:1600x1200@60  14:1280x1024@60  15:1024x768@60  16:2560x1600@60  17:1920x1200@60  18:1280x800@60  19:2560x1440@60  20:1920x1080@60  21:1600x900@60  22:1368x768@60  23:1280x720@60 
        Geometry: 1920,7 1707x1067
        Scale: 1.5
        Rotation: 1
        Overscan: 0
        Vrr: Automatic
        RgbRange: unknown
        HDR: incapable
        Wide Color Gamut: incapable
        ICC profile: none
        Color profile source: sRGB
Output: 2 DP-5
        enabled
        connected
        priority 2
        DisplayPort
        Modes:  0:1920x1080@60*!  1:1920x1080@60  2:1920x1080@60  3:1920x1080@30  4:1920x1080@30  5:1920x1080@24  6:1920x1080@24  7:1600x1200@60  8:1680x1050@60  9:1400x1050@60  10:1280x1024@60  11:1440x900@60  12:1360x768@60  13:1280x800@60  14:1280x720@60  15:1280x720@60  16:1280x720@60  17:1024x768@75  18:1024x768@70  19:1024x768@60  20:800x600@75  21:800x600@72  22:800x600@60  23:800x600@56  24:720x480@60  25:720x480@60  26:720x480@60  27:720x480@60  28:720x480@60  29:640x480@75  30:640x480@73  31:640x480@60  32:640x480@60  33:640x480@60  34:720x400@70  35:1280x1024@60  36:1024x768@60  37:1280x800@60  38:1920x1080@60  39:1600x900@60  40:1368x768@60  41:1280x720@60 
        Geometry: 0,0 1920x1080
        Scale: 1
        Rotation: 1
        Overscan: 0
        Vrr: incapable
        RgbRange: unknown
        HDR: incapable
        Wide Color Gamut: incapable
        ICC profile: none
        Color profile source: sRGB
Comment 3 Owen 2024-08-02 18:51:02 UTC
Just found out that the issue does not occur if the main monitor is at 160% scale. I also just discovered another issue, #459373 (https://bugs.kde.org/show_bug.cgi?id=459373) that seems to be similar, but it was on the bottom edge, was visual as well (there is no gap visually with this issue), and is marked as fixed. Possibly still related though.
Comment 4 fanzhuyifan 2024-08-03 06:04:07 UTC
Marking as duplicate of 459373. Feel free to reopen if the issue persists on git master or the upcoming 6.2 release.

*** This bug has been marked as a duplicate of bug 459373 ***
Comment 5 Owen 2024-08-03 06:17:13 UTC
(In reply to fanzhuyifan from comment #4)
> Marking as duplicate of 459373. Feel free to reopen if the issue persists on
> git master or the upcoming 6.2 release.
> 
> *** This bug has been marked as a duplicate of bug 459373 ***

didn't notice that the fix was in an upcoming release. I'm not sure if it's the exact same issue, since that one is also visual, but I'll wait for 6.2.0 and reopen then if it doesn't fix the problem.