icons missing after 2 fingers/horizontal scrolling on the dock

[Wolf Rogner]

since the upgrade of gnome-session from 3.25.90 to 3.26.0 I observe weird visual phenomena.

1. Icons in the task bar disappear (and only appear after logout/login)
2. Windows get drawn with black margins and sometimes with black canvas (gets away after a second or so)

Issue can be related to upgrade of libmutter (libmutter-1-0:amd64 3.25.91+20170902~ce515c5-1ubuntu1 -> 3.26.0-1)

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: gnome-session (not installed)
ProcVersionSignature: Ubuntu 4.13.0-11.12-generic 4.13.1
Uname: Linux 4.13.0-11-generic x86_64
ApportVersion: 2.20.7-0ubuntu1
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Fri Sep 15 12:33:43 2017
InstallationDate: Installed on 2017-09-05 (9 days ago)
InstallationMedia: Ubuntu 17.10 "Artful Aardvark" - Alpha amd64 (20170902)
SourcePackage: gnome-session
UpgradeStatus: No upgrade log present (probably fresh install)

[Wolf Rogner (war-rsb)]

Figured out how to reproduce this:

Appended screenshot 1 demonstrates how my favorites bar looks like normally.

When scrolling down with two fingers with the mouse over the bar, the icons are gone (see screenshot 2).

Icons cannot be called back by reverse scrolling with the mouse cursor in the favorites bar.

Workaround: Screen-lock and unlock will bring up the fav-bar correctly.

[Sebastien Bacher (seb128)]

is that still an issue?

[Wolf Rogner (war-rsb)]

Yes it is.
I found some more evidence to this:

1. It only seems to happen with a bluetooth mouse that allows two finger scrolling on the surface (I use an Apple Magic Mouse). Thus, it cannot be reproduced using pure two-finger swipe down on the dock any more.

2. Swiping up does not reveal the icons any more.

3. workaround:

$ gsettings set org.gnome.shell.extensions.dash-to-dock dock-position 'LEFT'

as ctrl-alt T opens a terminal this can be entered quite simply (especially when aliasing the command above)

I have no more information as of why this might happen.

[Sebastien Bacher (seb128)]

the issue seems similar to bug #1727363

[Wolf Rogner (war-rsb)]

Yes, I can confirm that scrolling right triggers the same effect.
Curious.

However, the dock does not crash, just the icons disappear.

[Sebastien Bacher (seb128)]

right, I think the "crash" is just a wording issue from the user trying to describe the problem

[Launchpad Janitor (janitor)]

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

[Sebastien Bacher (seb128)]

Could somebody with a device doing horizontal scrolling test in an upstream GNOME session if dash-to-dock has the same issue?

[Paulos (valach-pavel)]

Confirming with my Bluetooth MS mouse.

Adding a workaround:
you can lock your session. After unlocking, the icons will reappear.

[Wolf Rogner (war-rsb)]

I have established a workaround which involves no session locking

from a terminal window:
$ gsettings set org.gnome.shell.extensions.dash-to-dock dock-position 'LEFT'

I added an alias to my .bash_aliases to speed the process.
LEFT can be substituted to where your bar is ({'TOP','RIGHT','BOTTOM','LEFT'}).

[Paulos (valach-pavel)]

Replying to seb128:
Current Dash to Dock from extensions.gnome.org installed on the same system does not suffer from the same issue.

[Daniel Rodriguez (newhacker1746)]

I can confirm this bug, and the workaround with gsettings works. I encountered this same bug on two different machines on 18.04, both updated multiple times daily, one with a Logitech mouse + unifying receiver and the other with a standard Apple wired mighty mouse, on both Wayland and Xorg.
I think this bug is quite universal, the Logitech mouse machine uses Xorg daily with an HD 5570 and the mighty mouse machine uses Wayland daily with a GTX 760 (nouveau).

Since it occurred with a wired mighty mouse (and a dongle wireless USB mouse), I don't think it is specific to bluetooth mice. It also occurs when scrolling horizontally with the scroll "ball" that can scroll in all directions.

The same issue also occurs for me when scrolling horizontally or vertically on the popup menu from single-clicking an app with multiple dots/instances, by that I'm referring to the menu with all the instances listed (like gnome-terminal) and that allows one to choose which one to bring to the front.

[Diogo (dpc90)]

The issue seems to be even worse in Ubuntu 20.04 LTS. A two-finger horizontal scroll on the dock will make the system (almost) irresponsive: no response to keyboard, only the mouse cursor moves, but clicking anywhere has no effect. Icons on the dock do not disappear anymore, though. I have to close the laptop lid to force suspend so I can control the system again.

[Diogo (dpc90)]

In my system, disabling IMWheel (https://wiki.archlinux.org/index.php/IMWheel) solves the problem.

[Daniel van Vugt (vanvugt)]

Diogo, that sounds like a different bug. Please open a new bug.

[Daniel van Vugt (vanvugt)]

Thank you for reporting this bug to Ubuntu.
Ubuntu 17.10 (artful) reached end-of-life on July 19, 2018.

See this document for currently supported Ubuntu releases:
https://wiki.ubuntu.com/Releases

We appreciate that this bug may be old and you might not be interested in discussing it any more. But if you are then please upgrade to the latest Ubuntu version and re-test. If you then find the bug is still present in the newer Ubuntu version, please add a comment here telling us which new version it is in.

[Launchpad Janitor (janitor)]

[Expired for gnome-shell-extension-ubuntu-dock (Ubuntu) because there has been no activity for 60 days.]