Bug 457698

Summary:	Changing display scale on Wayland requires users to log out and log back in.
Product:	[Applications] systemsettings	Reporter:	Joshua T <joshuaandrewtr>
Component:	kcm_kscreen	Assignee:	kscreen-bugs-null <kscreen-bugs-null>
Status:	RESOLVED UPSTREAM
Severity:	normal	CC:	nate, plasma-bugs-null
Priority:	NOR
Version First Reported In:	master
Target Milestone:	---
Platform:	Neon
OS:	Linux
URL:	https://bugreports.qt.io/browse/QTBUG-78327
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Joshua T 2022-08-10 00:39:48 UTC

SUMMARY
Changing the display scaling on Plasma Wayland session causes a blurry taskbar, launcher, and applets. This requires the user to log out and log back in (or restart plasmashell).

STEPS TO REPRODUCE
1. Change display scaling on Plasma Wayland session.

OBSERVED RESULT
Panels and applets are blurry after changing display scale. 


EXPECTED RESULT
My proposal to this problem is to have Plasmashell automatically restart when a display scale is changed on the wayland session. The same animation shown when logging in should be shown while plasmashell is restarting. This way, users will not have to log out to get crisper scaling. I currently do not know how to code, so I can't implement this myself. However, It would be great if someone could make this idea reality!


SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 5.25.80

Comment 1 Nate Graham 2022-08-10 17:56:12 UTC

This issue affects all Qt apps (not just Plasma) and is unfortunately caused by a Qt bug: https://bugreports.qt.io/browse/QTBUG-78327.

Comment 2 Joshua T 2022-08-12 21:09:31 UTC

(In reply to Nate Graham from comment #1)
> This issue affects all Qt apps (not just Plasma) and is unfortunately caused
> by a Qt bug: https://bugreports.qt.io/browse/QTBUG-78327.

But restarting Plasma-shell after a display scale is changed would be more user-friendly. Then users would not have to log out. There could also be a tooltip that warns users that some apps will not respond to scaling until they are closed and reopened. I believe Windows has a feature like that.

Comment 3 Nate Graham 2022-08-12 21:17:06 UTC

It's not just Plasma; you need to restart all Qt-based apps to get them to notice the new scale factor.

But yeah, we can add an info message that informs the user of this.

Comment 4 Joshua T 2022-08-13 02:22:44 UTC

(In reply to Nate Graham from comment #3)
> It's not just Plasma; you need to restart all Qt-based apps to get them to
> notice the new scale factor.
> 
> But yeah, we can add an info message that informs the user of this.

Great!