Bug 474641

Summary: Window to Next/Previous Screen shortcut is broken at certain display scales for maximized applications
Product: [Plasma] kwin Reporter: miranda
Component: multi-screenAssignee: KWin default assignee <kwin-bugs-null>
Status: REPORTED ---    
Severity: normal CC: fanzhuyifan, miranda, natalie_clarius, nate
Priority: NOR Keywords: multiscreen, wayland-only
Version First Reported In: 5.27.8   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description miranda 2023-09-18 04:24:39 UTC 
STEPS TO REPRODUCE
1. Have multiple monitors (in my case, dual 4k)
2. Set display scale factor to a non-square value (in my case, anything above 1.5 or below 2.0)
3. Maximize an effected application (in my situation, Konsole is an easy way to reproduce)
4. Hit "Window to Next/Previous Screen" shortcut (in my case, that's Meta+Shift+Right/Left)

OBSERVED RESULT
The window is stuck on the first monitor until either plasmashell or the window is interacted with

EXPECTED RESULT
Window moves to other monitor

SOFTWARE/OS VERSIONS
Linux Version: 6.5.3-arch1-1
KDE Plasma Version: 5.27.8
KDE Frameworks Version: 5.110.0
Qt Version: 5.15.10
KWin Backend: Wayland
Mesa 23.1.7 (AMD RX 6600 XT)

ADDITIONAL INFORMATION
At this resolution and display size (4k @ 27in/69cm) a display scale of ~175% is required to make things large enough so I don't have to squint, but not so large the buttons approach the size of a fisher price toy.

Normally I'd just drag and drop windows from one monitor to the other, but that's broken too (see bug #449105).

This only impacts certain windows. XWayland applications work. Konsole, Firefox (wayland enabled), Dolphin, and others are impacted. I'd assumed this is only broken for Wayland applications but System Settings seems to work fine, oddly enough.

I have not tested this on X11.
Comment 1 fanzhuyifan 2024-02-01 03:03:07 UTC 
Can't reproduce on master. Under wayland, with multiple displays with different scaling, I can consistently use the shortcuts to move windows back and forth between the different screens.
Comment 2 miranda 2024-02-01 06:36:55 UTC 
What scale factors did you try, and what resolution displays do you have?

I can consistently reproduce the issue at a variety of scale factors. When both monitors match their scale percentage, I can reproduce it more reliably. I recommend starting at ~155% both displays, bumping up 5% for both each time, and using a maximized Dolphin window to test (that in particular is susceptible).
Comment 3 miranda 2024-02-01 06:39:17 UTC 
(In reply to miranda from comment #2)
> What scale factors did you try, and what resolution displays do you have?
> 
> I can consistently reproduce the issue at a variety of scale factors. When
> both monitors match their scale percentage, I can reproduce it more
> reliably. I recommend starting at ~155% both displays, bumping up 5% for
> both each time, and using a maximized Dolphin window to test (that in
> particular is susceptible).

Wait, you're on main, not RC1. And it looks like RC2 just came out. I'll let you know
Comment 4 miranda 2024-03-08 08:00:06 UTC 
This is still an issue on KDE 6.0.1.

I figured out how to reproduce it more reliably. You want to make sure your monitors are offset at least a bit, rather than having shared corners/edges side by side. The left monitor is slightly higher vertically than the right.

I'd normally just change it so all the corners are shared, but I have them slightly askew to work around a much more annoying issue, 451744.