Bug 453445

Summary:	Scaling setting is no longer honored after some time
Product:	[Plasma] KScreen	Reporter:	Max <bugs.kde-max.seifert>
Component:	kded	Assignee:	kscreen-bugs-null <kscreen-bugs-null>
Status:	RESOLVED FIXED
Severity:	minor	CC:	nate
Priority:	NOR	Keywords:	multiscreen, usability
Version First Reported In:	5.24.4
Target Milestone:	---
Platform:	Debian testing
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Max 2022-05-05 23:05:04 UTC

SUMMARY

I've witnessed screen scaling to behave strange at times. I run a dual-head setup with HiDPI monitors. The scaling is set to 1.5 in kcm_kscreen. Applications get scaled fine then.
After using the machine for some time, any new application started is scaled as if the scaling was set to 1.0.

My current work-around is to then close the application, get back to kscreen settings, where I see the scaling as 1.5 (the value I want). I set it to something different → apply. I set it back to 1.5 → apply.
Starting another app will render it correctly.


STEPS TO REPRODUCE
1. See applications scaled correctly as set in kscreen configuration
2. Work for some time
3. Start any new application GUI process

OBSERVED RESULT
The started application is not rendered in configured scaling.


EXPECTED RESULT
The started application is rendered in configured scaling.

SOFTWARE/OS VERSIONS
Windows: n/a
macOS: n/a
Linux/KDE Plasma: Debian (testing)/ 5.24.4
(available in About System)
KDE Plasma Version: 5.24.4
KDE Frameworks Version: 5.24.4
Qt Version: 5.15.2+dfsg-16+b1

ADDITIONAL INFORMATION

Comment 1 Max 2022-05-05 23:12:02 UTC

I would also be happy with a work-around that allows me to set scaling from command line. I am filing this bug because my investigation into "can I poke D-Bus and just set this?" did not bring up any success for me.

If this is something that can be detected or solved programmatically, I'm happy for suggestions and ideas. I'm equally happy to try patches to kscreen or submit patches myself. This may be a good opportunity to thaw my dated C++/Qt skills.

Please let me know if I you need any further info!

Comment 2 Nate Graham 2022-05-06 15:20:29 UTC

I've intermittently seen this on Wayland myself, but haven't been able to get a reproducible test case. Are you experiencing it on Wayland or X11?

Please feel free to poke around in the code and work on a patch!

Comment 3 Max 2022-05-17 21:06:14 UTC

I'm using X11 only. As you've already mentioned, it is difficult to get close to a reproducible test case. As I have approximately 0 knowledge of plasma's inner work, it's even more challenging to get to reproducible scenarios.
For what it's worth, I'm relieved to hear I'm not the only one facing this.

I'll make sure to update here in case I find something.

Comment 4 Max 2022-09-19 07:12:32 UTC

5.25.4-2 appears to no longer show this behavior.
So, this was either addressed and fixed directly or as a side effect (maybe?)  of config sync updates.
My gratitude goes out to the kwin & plasma teams - thank you people for keeping up the good work!