XWayland applications respect scale only if a scaled output is primary on a mixed-scale setup

[Ben Aceler]

The bug occurs with any XWayland application. I tried VSCode, Chrome, Audacity, Darktable...

I have two monitors with a different DPI. One is 4K HiDPI monitor and the second in LowDPI 2K monitor. I can setup 200% scale for a HiDPI monitor and 100% scale for a LowDPI. All native gnome applications are fine.

The bug: when I select LowDPI monitor as a primary, XWayland applications stop scaling on a HiDPI monitor. They run 100% scale on both monitors. If I select HiDPI monitor as the primary, XWayland applications scales 200% on both monitors.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: mutter 3.36.6-1ubuntu0.20.04.2
ProcVersionSignature: Ubuntu 5.4.0-52.57-generic 5.4.65
Uname: Linux 5.4.0-52-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.10
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Sat Nov 7 12:28:53 2020
InstallationDate: Installed on 2019-11-16 (356 days ago)
InstallationMedia: Ubuntu 19.10 "Eoan Ermine" - Release amd64 (20191017)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=ru_RU.UTF-8
 SHELL=/bin/bash
SourcePackage: mutter
UpgradeStatus: Upgraded to focal on 2020-05-02 (189 days ago)

[Daniel van Vugt (vanvugt)]

I'm not sure how Xwayland communicates the scale info to apps, but adding a xorg-server task anyway. Because that's the source package of Xwayland.

[Daniel van Vugt (vanvugt)]

Please report the bug to the developers at:

  https://gitlab.gnome.org/GNOME/mutter/issues

and then tell us the new issue ID.