Non-integer X11 scaling causes mouse from login screen to stick around

[Ryan Thompson]

If you enable fraction scaling and then login using an X11 session, the mouse cursor that existed on the login screen (gdm3) will persist after logging in. This mouse cursor continues to exist at the same pixel coordinates as when the login was completed. A new mouse cursor is then created for that login, which is controlled by the mouse. The original cursor that persisted from the login screen now becomes static and can no longer be moved. However, like any mouse cursor, it hovers over all windows and the desktop, which is quite distracting when the cursor is in the middle of the screen.

This extra mouse cursor can be eliminated by switching to a non-fractional scaling mode. Once it is eliminated, you can then switch back to fractional scaling and the extra cursor will not return. Seeing this, I have worked around this issue by adding a startup script to my session that toggles the scaling mode between integer scaling and my desired fractional scaling mode. Obviously this adds a bit of extra flicker to the login process, though, so it's not ideal.

Note that a similar bug has been reported previously (#1827428), but that bug was closed in the Ubuntu 19.04 EOL.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: gnome-shell 3.36.1-5ubuntu1
ProcVersionSignature: Ubuntu 5.4.0-26.30-generic 5.4.30
Uname: Linux 5.4.0-26-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Mon Apr 27 09:49:40 2020
DisplayManager: gdm3
InstallationDate: Installed on 2020-03-20 (37 days ago)
InstallationMedia: Kubuntu 19.10 "Eoan Ermine" - Release amd64 (20191017)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
RelatedPackageVersions: mutter-common 3.36.1-3ubuntu3
SourcePackage: gnome-shell
UpgradeStatus: Upgraded to focal on 2020-04-23 (4 days ago)

[Daniel van Vugt (vanvugt)]

Sounds like a duplicate of bug 1873052. See also bug 1875528.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.