Distorted mouse pointer in the remote window

[Simon Sadetsky]

Distorted mouse poitner in the remote window (see the photo attched)

The bug is reproducable with Wayland only. Whith xorg all works fine on the same machine. I experience it more than a year.

I'm using fraqtional scale 125%.

$ gsettings get org.gnome.mutter experimental-features
['x11-randr-fractional-scaling', 'scale-monitor-framebuffer']

Video is AMD integrated Radeon 4750G.

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: gnome-remote-desktop 42.9-0ubuntu0.22.04.1
ProcVersionSignature: Ubuntu 6.2.0-39.40~22.04.1-generic 6.2.16
Uname: Linux 6.2.0-39-generic x86_64
ApportVersion: 2.20.11-0ubuntu82.5
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: ubuntu:GNOME
Date: Fri Jan 19 15:35:25 2024
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=ru_RU.UTF-8
 SHELL=/bin/bash
RebootRequiredPkgs: Error: path contained symlinks.
SourcePackage: gnome-remote-desktop
UpgradeStatus: Upgraded to jammy on 2022-06-05 (592 days ago)

[Pascal Nowack (pnowack)]

This is a mutter issue. The cursor data is provided in an incorrect way from there.

[Daniel van Vugt (vanvugt)]

Possibly related to bug 2011575 and https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/6470

[Pascal Nowack (pnowack)]

It looks more like a stride issue to me. There were no such reports in the past about normal setups, i.e. setups, where the experimental fractional scaling setting is not used.
There were several reports and fixes about wrong strides and co with the experimental fractional scaling however, like https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/976, https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/415, or https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1855 (all related to that setting).

So, disabling that experimental setting should work around that issue, I think. Another thing to test would be, whether current GNOME versions (45, upcoming 46) are also affected, or whether they are already fixed here.

[Daniel van Vugt (vanvugt)]

Good point. I mistook the warped-ness for one of many previous bugs to do with zombie duplicate cursors.

[Simon Sadetsky (ssadetsky)]

With non-factional scale like 100%/200% the issue is not reproducible.

Also, rare after OS restart the pointer is correct, but then there is an another issue: pointer cannot "touch" the upper edge of the screen so the autohided top bar does never show up on the remote screen.