https://bugs.kde.org/show_bug.cgi?id=446948
Bug ID: 446948
Summary: Qt apps scaling breaks in multi-monitor setup with 90
degree rotation
Product: kwin
Version: 5.23.4
Platform: Archlinux Packages
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: wayland-generic
Assignee: kwin-bugs-n...@kde.org
Reporter: bugs-...@lagiewka.pl
Target Milestone: ---
Created attachment 144521
--> https://bugs.kde.org/attachment.cgi?id=144521&action=edit
Screen arrangement
SUMMARY
When a scaled display is on the right of another display that is rotated 90
degrees anticlockwise, moving Qt-based apps between them will eventually break
scaling.
See the attachment for the layout. Happens for both clockwise and
anticlockwise. I've first thought that it might have something to do with the
display's virtual "chin" being in the way (as is in the illustration), but this
is not the case when rotated the other way.
STEPS TO REPRODUCE
1. Get two displays
2. Rotate the display on the left 90 degrees (anti)clockwise
3. Scale the display on the right to 200%
4. Open a Qt app on left (100% scale) display
5. Move the app to the right screen
6. Move the app to the left screen
7. Move the app to the right screen
1. Get two displays
2. Rotate the display on the left 90 degrees (anti)clockwise
3. Scale the display on the right to 200%
4. Open a Qt app on right (200% scale) display
5. Move the app to the left screen
6. Move the app to the right screen
OBSERVED RESULT
After each set of steps the Qt app will not keep the scale (will be blurry).
EXPECTED RESULT
Flipping windows back and forth between screens for hours doesn't break
scaling. Amazing.
It's worth mentioning that this does not happen if the scaled display is on the
left. I have already filed a bug regarding context menu
(https://bugs.kde.org/show_bug.cgi?id=446563) which is subject to the same
layout rules, but is reproducible _without_ any rotation. If one of the
displays is scaled - things on the right display can break.
Tested with scaled display above and below - works. Only when on the right -
this happens.
SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux
KDE Plasma Version: 5.23.4
KDE Frameworks Version: 5.88.0
Qt Version: 5.15.2+kde (KDE patches in main repos for some packages)
ADDITIONAL INFORMATION
This doesn't happen for non-Qt apps - Firefox, Electron (Ozone) and other Gtk
apps (I've tested Gnome's Files / Nautilus) work just fine.
I've no idea whether this is Qt or KWin issue. The fact that this happens only
for certain screen arrangements makes me think this might be KWin as well.
--
You are receiving this mail because:
You are watching all bug changes.
