Bug 489461

Summary:	Windows are moved to a different monitor when screen is woken up
Product:	[Plasma] kwin	Reporter:	equeim
Component:	multi-screen	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED DUPLICATE
Severity:	normal	CC:	kde, kde, linx.system.adm, nate, xaver.hugl
Priority:	NOR	Keywords:	multiscreen
Version:	6.1.1
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description equeim 2024-06-29 20:02:47 UTC

SUMMARY
I have dual monitor setup with Dell S2340L connected via HDMI and placed on the left, and Gigabyte G27Q connected via DisplayPort and placed on the right. Sometimes when screen is turned on after being turned off by timeout (not suspend/sleep, just "turn off screen" option in power management settings), some windows that were on the right monitor are moved to the left one. This doesn't happen every time, and not to all windows (most stay where they were).

This is with Plasma Wayland, GPU is Radeon 6700XT.

STEPS TO REPRODUCE
1. Place a window on the right monitor
2. Wait until screen is turned off
3. Wake screen by mouse/keyboard

OBSERVED RESULT
Sometimes window is moved to the left monitor.

EXPECTED RESULT
Windows stays where they are

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: openSUSE Tumbleweed
KDE Plasma Version: 6.1.1
KDE Frameworks Version: 6.3.0
Qt Version: 6.7.2

Comment 1 equeim 2024-07-01 02:02:43 UTC

Additional info: it happens when screen is turned on before screen locker kicks in (you may need to disable automatic screen locking to reproduce this), and one monitor needs to take visibly more time to turn on than the other (in my case the difference is more than 1 second).

Comment 2 Maxime Poulin 2024-07-06 08:31:08 UTC

I'm having the same issue on ArchLinux with KWin 6.1.1.2-1 from the official repos.

For me, it happens even with the screen locker. My left monitor takes up several seconds to wake up. Connected via HDMI. In fact the delay is large enough if I start typing my password on the lock screen before that monitor woke up, it steals the password input because the password field moves to that monitor when waking up (but that's a separate issue).

I just come up to my computer long after the screen locked and turned off all 3 monitors. I wake it up, input my password to unlock the computer, and the windows from my left monitor are now on the center monitor. Things that are full screen or maximized tend to be more affected. In fact, unmaximizing a window from that monitor briefly flickers it on the center monitor. The computer itself is a desktop and never goes to sleep. Nothing but a fresh session seems to fix that glitch.

I believe this is a regression from 6.0, this didn't happen with 6.0. It might even be a regression from 6.1.0 as it started happening in the last week or two.

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Possibly offtopic, let me know if I should open another bug report, but there seems to be a deeper issue related to the handling of monitors that disconnect from the system when they go to sleep: there was the issue of windows appearing on the wrong panel (fixed), there's the issue I mentioned with the lockscreen, there's this issue. They all seem to stem from the same root cause: the monitor disconnects from the system when it goes to sleep.

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One way to reproduce easily on my end is, lock the screen and then press ESC which fades to black and turns off the screens immediately. Once that monitor has done the blue NO SIGNAL screen and goes to sleep, I can wake up the monitors back up and reproduce the bug.

Comment 3 David Edmundson 2024-09-25 12:50:55 UTC


*** This bug has been marked as a duplicate of bug 490667 ***