Bug 429391

Summary:	Window outlines in Pager ignore desktop scaling
Product:	[Plasma] plasmashell	Reporter:	R David Dunphy <rdd.dunphy>
Component:	Pager widget	Assignee:	Eike Hein <hein>
Status:	RESOLVED FIXED
Severity:	normal	CC:	nate, plasma-bugs, rdd.dunphy
Priority:	NOR
Version First Reported In:	5.18.5
Target Milestone:	1.0
Platform:	Ubuntu
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description R David Dunphy 2020-11-20 12:10:20 UTC

If the display scale factor is set to more than 100%, the window outlines in the Pager preview are not displayed correctly. E.g. if you set the display scale factor to 200%, only windows in the top left quarter of the screen are shown, and windows that only take up that quarter of the screen are displayed as if they occupy the entire screen. (So the preview is actually a preview of the top left portion of the desktop, not the entire desktop.)

STEPS TO REPRODUCE
1. In Display configuration, set Global scale to 200% 
2. Log out and back in again
3. Open a Konsole window and position it in the middle of the screen

OBSERVED RESULT
In the Pager widget, the window outline for the Konsole screen is in the bottom right corner of the desktop preview.

EXPECTED RESULT
Window outline should be in the centre of the preview.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Ubuntu 20.04
KDE Plasma Version: 5.18.5
KDE Frameworks Version: 5.68.0
Qt Version: 5.12.8

Comment 1 R David Dunphy 2020-11-20 13:09:54 UTC

Just realised this issue is mentioned in https://bugs.kde.org/show_bug.cgi?id=356446, but I think it's probably a separate bug.

Comment 2 Nate Graham 2020-11-20 20:01:33 UTC

I suspect this will end up being a duplicate of 356446, yes. Most of the issues in the duplicates of it aren't fixable generically and can only really be fixed by using Qt scaling.

Can you please attach a screenshot? And can you tell me if it's fixed if you use the Wayland session or set PLASMA_USE_QT_SCALING=1 and restart plasmashell in your X11 session?

Comment 3 R David Dunphy 2020-11-21 14:17:33 UTC

Running plasmashell with PLASMA_USE_QT_SCALING=1 doesn't seem to help, but using Wayland fixes the issue. Here's a screenshot on X11 with a scale factor of 200%: https://ibb.co/3fTKjS6

Comment 4 Nate Graham 2020-11-21 16:49:32 UTC

Ah then this is caused by a mismatch between the size that KWin knows and the size that Plasma knows, which is only really fixable on Wayland unfortunately (they have the same coordinate space there).

Hopefully you will be able to use the Wayland session. :)