When zoom is enabled, mouse pointer leaves square trails on desktop

[Christopher Patti]

Problem:

When you turn on Zoom from the Accessibility menu, the mouse leaves square shaped trails as it moves.

Steps to Reproduce:

1. Under the Settings applet's Accessibility menu, turn on Zoom.
2. Observe the mouse cursor leaving little square patterns wherever it goes, obscuring whatever you're trying to work on.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: gnome (not installed)
ProcVersionSignature: Ubuntu 5.4.0-21.25-generic 5.4.27
Uname: Linux 5.4.0-21-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu26
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Tue Apr 14 21:50:16 2020
InstallationDate: Installed on 2020-01-09 (96 days ago)
InstallationMedia: Ubuntu 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
SourcePackage: meta-gnome3
UpgradeStatus: Upgraded to focal on 2020-01-24 (82 days ago)

[Christopher Patti (feoh)]

OK so I took a screencast to try to capture the issue, and it does show up although the screencast renders the trail left behind the cursor as square blobs rather than outlines.

[Ted Colman (tcolmn1)]

Hi,

I have the exact same problem after upgrading to Ubuntu 20.04 from
Ubuntu 18.04. I have found that the issue goes away when I disable zoom
in Settings -> Universal Access. This was never an issue in Ubuntu 18.04
for me with zoom enabled. At least now I know I can work around this
issue by just turning off zoom but it'd be great if there was a real fix
for this issue.

Have you gotten any response on the fix for this bug or have you found
out yourself how to fix?

Thanks,
Ted

[Christopher Patti (feoh)]

Hi Ted!

I'd upgraded from 19.10 myself.

I haven't heard of any response, and while I tried to research the problem (I have a fair set of tech chops) I got lost in the weeds as to even which subsystem in particular I should be reporting it under, much less what steps I could take to put some more technical meat on the bones of this issue.

I've since gone over to Elementary for the moment (and probably for the long haul. I LOVE it!) so I'm no longer having this problem, but we'll see what happens when Elementary releases Odin, their 20.04 based release, in the future.

[Fred Shaw (genericness)]

Hi Ted,

I was experiencing this too! Your fix worked for me... disabled zoom: no more trails.

I seemed to only get the on the desktop background ... each set of trails would clear themselves after a second or two, and they seem to be flickering a bit, so perhaps they are only appearing in the display buffers. Maybe to do with NVidia proprietary drivers?

Cheers,

Fred

[Christopher Patti (feoh)]

Glad to hear you guys are in good shape.

Being partially blind and fine&gross motor impaired, "Disable zoom" might as well be "Lop off an arm".

(I'm actually not kidding. Key chorded zoom is how I can actually make use of a computer. Again Elementary excels at this)

[kaungzayarmoe (kaung7192)]

Hi,
I just wanted to thank the one who mentioned about disabling the zoom. It really worked for my pop os 20.04. But I still wish for a proper solution though. Anyway, thank you.

[Launchpad Janitor (janitor)]

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

[Roland Bertolom (bertolom-1)]

Indeed, disabling zoom works. Though, it's not an option for me, because I need it for work (not that much as Christopher, though).

[Frans van der Sommen (fransvandersommen)]

RE: mouse pointer leaves square trails-boxes

Hello Christopher,

Last week I moved to Ubuntu 20.04, and have the same distracting
trails-boxes, that indeed disappear when Zoom is Off, but I absolutely need
the Zoom.

I have written a small script that toggles Zoom, and added it as a
short-cut. Now, with a single key-press, I can toggle between Zoom On (for
my eye sight) and Zoom Off (for a full desktop view, without the
trails-boxes).

If you are interested, I will email you the details,

Som

<email address hidden>

[Atsawin Chaowanakritsanakul (joke-p)]

Though, I use zoom not as frequent, maybe once or twice a day, disable Zoom is not comfortable for me, too.

I found that there is a short cut for enable/disable zoom. Along with other short cuts, they are:

Super + Alt + 8 = Toggle zoom
Super + Alt + = = Zoom in
Super + Alt + - = Zoom out

https://askubuntu.com/questions/82398/how-to-zoom-in-zoom-out

[Christopher Patti (feoh)]

Oh wow. Confirming that this bug not only still exists but is even more severe (shows up in pretty much every application) in Groovy Gorilla dailies.

[Christopher Patti (feoh)]

Also to clarify, it's no longer just the desktop background. With a clean install of 20.10, the mouse pointer now scribbles over everything with a square pixel eraser.

[E2rd (r-ubunt3-5)]

I've just found when /org/gnome/desktop/interface/enable-animations changed to false in dconf, I see no rectangles. However, mouse cursor starts to lag which is even worse.

[Christopher Patti (feoh)]

Can also confirm on Pop!_OS 20.10 on a Thelio R2 with AMD graphics. I'd thought maybe this was an Nvidia binary blob issue but maybe it's a core Gnome issue.

Good luck to any partially blind person trying to use this :\

[Christopher Patti (feoh)]

Hi everyone!

Let me just say that System76's awesome lifetime support just showed itself to be PRICELESS in my book!

Nathan from System76 gave me the following work-around, and it WORKED!

Add:

```
CLUTTER_PAINT=disable-clipped-redraws:disable-culling
```

to /etc/environment and reboot! For me anyway on Pop! OS 20.10, no more zoomed mouse cursor trails!

[Randy Winchester (randy)]

I've been running 20.10 since November 2020 and the pointer scribbling just started up during the last week after an update or new software installation. I'm not sure what might have caused it to start.

I can confirm that disabling Zoom in system settings/accessibility does make it go away.

For those that require Zoom, see the previous message (#16) from Christopher Patti:

Add:

```
CLUTTER_PAINT=disable-clipped-redraws:disable-culling
```

to /etc/environment and reboot! For me anyway on Pop! OS 20.10, no more zoomed mouse cursor trails!

This also works and allows Zoom to be on.

[Christopher Patti (feoh)]

Just an update to #17 - I've since had to turn this off because it destabilized my Pop! OS install terribly. I was seeing 3-5 hard lockups a day.

Since I turned it off it's been rock solid.

Still super sad that there aren't the resources necessary to fix such a show stopper for low vision people.

Maybe I could fund it personally? :)

[Christopher Patti (feoh)]

I bit the bullet and shot this happening with my smart phone. Apologies for the video quality but this should help showcase what a usability blocker this is:

https://youtu.be/tjDUHc6nlPs

[Chris Guiver (guiverc)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. Unfortunately, we cannot work on this bug because your description didn't include enough information. You may find it helpful to read "How to report bugs effectively" http://www.chiark.greenend.org.uk/~sgtatham/bugs.html. We'd be grateful if you would then provide a more complete description of the problem.

We have instructions on debugging some types of problems at http://wiki.ubuntu.com/DebuggingProcedures.

At a minimum, we need:

1. The specific steps or actions you took that caused you to encounter the problem.
2. The behavior you expected.
3. The behavior you actually encountered (in as much detail as possible).

Yes I acknowledge you've attempted to by adding gif & video evidence, however the bug has been reported on a package that was created 2019-October-18 and has received no updates since then, so what 'update' are you referring to? More specific details are needed.

It's very likely you've filed against an incorrect package, however too few details exist in the initial bug report for the issue to be identified, as what the 'update' was will be key.

Thank you!

[Christopher Patti (feoh)]

Hi there @guiverc thank you very much for the response.

I filed the bug using the automated 'ubuntu-bug' program and I'll admit it's a crappy bug.

I've updated it with a concise problem description and steps to reproduce.

As to which package it's in, could you please give me any advice on how I would know? I'm not familiar with Gnome's internal architecture, so it's impossible for me to guess whether the issue might be with Mutter, the compositor, the window manager, or the Heisenburg compensator.

I've re-read that standard debugging wiki page in detail, and it doesn't bring me any closer to understanding how I can dial this problem in any further.

You'll note that 12 others have reported they're experiencing this issue. I suspect anyone who's using a large monitor and tries to use Zoom will encounter it.

I'd have dropped this long ago and resigned myself to using Windows, but I think making Ubuntu accessible to the visually impaired is important, because even if you're not disabled like me *everyone* will lose visual acuity as they age.

Again, thank you for your response and all the work you do for Ubuntu!

[Chris Guiver (guiverc)]

You just made me laugh, thank you :) Hisenburg... LOL.

The correct package is not really your job, ideally a *bug triager* would have detected a filing against a imperfect package & corrected... I'm not a GNOME user, but if was GNOME related `gnome-shell` is likely what I'd have used (alas I don't know any better sorry).

You mentioned an update; which I felt was significant. What update it was is likely key (I think so anyway), be it a kernel update, I'd likely change to the `linux` kernel package. It may also be related to your graphics driver (ie. kernel module), but I don't know what that is (I see nvidia in the details, that maybe key too).

You used `ubuntu-bug` to file this bug, that's usually very helpful, so thank you. If it was filed with `ubuntu-bug linux` (ie. against the kernel) hardware details would have been obtained, alas the package you used cause less detail to be kept (the package the bug is filed against decides what is uploaded). None of that is your fault; you attempted & did well; esp. with the corrected bug description - thank you!

I would have changed package if I knew what to change it to, alas I don't know sorry. Ideally the 'not described well' paste (my comment #20 [with one line removed & two paragraphs only I wrote]) would have been asked soon after you filed your report & decision made, alas there are few volunteers. I only saw this b/c of a askubu question, which you likely have guessed. I know two people (developers) who'd likely react to this, but as a user (in my position) I can't see a solution currently that I can provide.

If it was me, I'd likely test for this on the development release (hirsute currently, what will be 21.04), as that's where the developers look for issues as its far easier for them to fix them there. If it occurs there, filing a new report against `linux` or even `gnome-shell` would I bet get the attention I believe you're after, and have the highest chance of success at a fix. If you hardware is capable of it, even doing this in a VM may suffice (rather than overwrite your existing system). I don't know the correct package, but I'd expect those (kernel or gnome-shell) to be corrected by a developer on filing (if they are wrong as I fear they are). If you file a new report, I'd provide the URL for this link (saving someone from having to find it), and I'd bet this would be marked a duplicate of that link, providing the confirmation & adding the 'heat' of this report to the new bug (even if the new bug is marked duplicate of this; more information will be gained & some goal reached I'd hope). My 2c.

FYI: Any other user (or affects me) reader of this could also do this, as a new report can be by any registered (launchpad) user and reports still linked.

[Christopher Patti (feoh)]

Thank you very much I will absolutely try this on 21.04 - I bought a System76 Thelio recently which I love love LOVE and I purposefully added an extra 5TB HD I could use as a scratch / play / random distribution drive.

I really REALLY appreciate the response. I love Linux and Ubuntu and want to be able to recommend it without recommendation to my visually disabled friends :)

Now, do I re-route the warp drive through the dilithium chamber or the transporter? :)

[Patrick Smyth (smythp)]

So as a number of people have already observed, this bug is kind of a showstopper for many using Gnome's magnification feature on a regular basis, and it should definitely be fixed sooner rather than later.

However, looking at the behavior of the bug, I noticed there were no trails when the zoom feature was on and zoomed in. They're only present if the zoom setting is at 1.0 but the zoom feature is on. As a workaround, I wrote a small script that adds some logic to zooming in and out. If the feature is off and a zoom in is requested, the zoom is set to 2.0 and then the zoom feature is turned on. If a zoom out is requested and the updated magnification would be less than 2.0, i.e. fully zoomed out, the new magnification is set and then the feature is disabled. So, if you use the script to zoom in and out, you won't see trails, since the zoom feature will be disabled at max zoom.

The script can be found on GitHub here:

https://github.com/smythp/gnome-magnifier-mouse-trails-workaround

I've provided some usage guidance in the README and added some xbindkeys settings in another file that will replicate the default Gnome zoom in and out shortcuts. I haven't tested it extensively, feel free to contribute or open an issue, though no promises as to quality here.

[Daniel van Vugt (vanvugt)]

The issue has been reported upstream so please consider keeping the conversation there:

https://gitlab.gnome.org/GNOME/mutter/-/issues/1678

[Launchpad Janitor (janitor)]

This bug was fixed in the package mutter - 41.3-1ubuntu1

---------------
mutter (41.3-1ubuntu1) jammy; urgency=medium

  * Merge with debian, includes these upstream changes:
    - window: Don't change workspaces of unmanaged windows (LP: #1933996)
    - backend: Reset idletime when unplugging the power cable (LP: #1945121)
    - clutter/text: Invalidate actor paint volume when it has changed
      (LP: #1882291)
    - backends/native: Ensure pointer is onscreen in input thread (LP: #1933186)
    - OSK Enter, space and backspace keys don't work when typing in Greek
      (LP: #1820523)
    - window: Don't change workspaces of unmanaged windows (LP: #1932328)
  * Remainig changes with debian:
    - debian/gbp.conf: update upstream branch to point to ubuntu/master
    - debian/patches/x11-Add-support-for-fractional-scaling-using-Randr.patch:
      + X11: Add support for fractional scaling using Randr

mutter (41.3-1) unstable; urgency=medium

  * New upstream release:
    - Check keyboard serials for activation
    - Fix mixed up refresh rates in multi-monitor setups (LP: #1788535)
    - Allow disabling HW cursors
    - Improve damage handling (LP: #1872870)
    - Consider xrandr flags for advertised modes
    - Ensure constraints after client resize
    - window-group: Disable culling when rendinging clone to offscreen buffer
    - Fix workspace switch animation in default plugin
    - Fix unfullscreening of window that were mapped fullscreen
    - Fix DMA-BUF screencasts with unredirected fullscreen windows
    - Fix orientation changes on devices with 90°

mutter (41.2-2) unstable; urgency=medium

  * Team upload
  * d/p/Consistently-pass-timestamp-as-uint64-when-creating-MetaS.patch:
    Add proposed patch to fix FTBFS on 32-bit architectures
  * d/patches: Update to 41.2-6-g7b64c159a
    - Surface damage viewport improvements
  * Update patch metadata with upstream status

mutter (41.2-1) unstable; urgency=medium

  * Team upload

  [ Simon McVittie ]
  * New upstream release
  * d/patches: Drop patches that were applied upstream
  * d/patches: Update to upstream gnome-41 branch commit 41.2-3-g5d0c26631
    - wayland: Check keyboard serials for activation
    - Sync refresh rate to the correct monitor for maximized/full-screen
      apps in a multi-monitor layout
    - Add a debug environment variable to disable hardware cursors for
      faulty hardware and drivers

  [ Laurent Bigonville ]
  * debian/rules: Disable systemd support on non-linux architectures

mutter (41.1-1) unstable; urgency=medium

  * Team upload
  * New upstream release
  * Drop a patch that came from upstream
  * Update Lintian overrides
  * Replace patches for #995929 with the version that was applied upstream
  * Remove workaround for #994806
  * d/libmutter-9-0.symbols: Ignore removal of clutter_stage_capture_into.
    Nothing else in Debian references this symbol, except for forks of
    the mutter codebase.

mutter (41.0-5) unstable; urgency=medium

  * Team upload
  * Merge packaging from unstable
    - No changes relative to 41.0-4, except for the changelog
  * Close #995929 via changelog.
    The patches in 41.0-4 seem to have been successful.
  * Release to...