App list not scrolling properly with touchpad when xserver-xorg-input-synaptics is installed

[Andy Jenkins]

Steps to reproduce (20.04), shell 3.36.1:

1. Open 'Show Applications' -> 'All'
2. Attempt to scroll through the pages using a touchpad.

Expected result:
Scrolls through pages of applications one at a time.

Actual result:
Scrolls to second page of applications but will go no further.
This happens whether two-finger or edge scrolling is used.

Using an actual mouse with a scroll wheel works as expected. Using this in conjunction with the touchpad reveals horribly broken behaviour:
- Clicking on the 'dot' for any of the pages will let the touchpad scroll at most one page in either direction, if the mouse is not moved
- Moving the physical mouse lets the 'momentum' of the touchpad scrolling advance the list further as expected.

Incidentally, the application menu doesn't honour the 'natural scrolling' setting for the touchpad in the mouse settings - I will file a separate bug report for this but it may be of interest for whoever looks at this.
---
ProblemType: Bug
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
DisplayManager: gdm3
DistroRelease: Ubuntu 20.04
InstallationDate: Installed on 2017-11-12 (903 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
NonfreeKernelModules: nvidia_modeset nvidia
Package: gnome-shell 3.36.1-5ubuntu1
PackageArchitecture: amd64
ProcVersionSignature: Ubuntu 5.4.0-28.32-generic 5.4.30
RelatedPackageVersions: mutter-common 3.36.1-3ubuntu3
Tags: focal
Uname: Linux 5.4.0-28-generic x86_64
UpgradeStatus: Upgraded to focal on 2020-04-30 (3 days ago)
UserGroups: adm cdrom dialout dip lpadmin plugdev sambashare sudo wireshark
_MarkForUpload: True

[Daniel van Vugt (vanvugt)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. Please execute the following command only once, as it will automatically gather debugging information, in a terminal:

apport-collect 1876628

When reporting bugs in the future please use apport by using 'ubuntu-bug' and the name of the package affected. You can learn more about this functionality at https://wiki.ubuntu.com/ReportingBugs.

[Andy Jenkins (andy-jenks)]

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[Andy Jenkins (andy-jenks)]

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[Andy Jenkins (andy-jenks)]

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[Andy Jenkins (andy-jenks)]

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[Andy Jenkins (andy-jenks)]

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[Andy Jenkins (andy-jenks)]

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[Sebastien Bacher (seb128)]

Could you report it upstream on https://gitlab.gnome.org/GNOME/gnome-shell/issues ?

[Launchpad Janitor (janitor)]

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

[Daniel van Vugt (vanvugt)]

1. Regarding the observation:

   > Scrolls to second page of applications but will go no further.

   Actually a default install only has two pages. The illusion of having more pages is bug 1870847. Is that the real problem here? Or have you installed extra apps to make more pages?

2. Please follow the request in comment #8.

[Daniel van Vugt (vanvugt)]

Actually, please also try disabling the ubuntu-dock extension via 'gnome-shell-extension-prefs' and tell us if the problem goes away after that.

[Andy Jenkins (andy-jenks)]

I can confirm that disabling ubuntu-dock does not make the problem go away, and that I have more apps to make more pages.

I have reported the issue upstream at: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/2868

[Honey Yadav (hengifer)]

I had same problem, but after removing xserver-xorg-input-synaptics and other touchpad related drivers except xserver-xorg-input-libinput, and then rebooting it got solved.
See if that helps :)

[Andy Jenkins (andy-jenks)]

I can confirm that the problem disappears after removing xserver-xorg-input-synaptics, but there's also now no 'momentum' when scrolling and the mouse feels a bit odd in a way I can't quite describe. I'll mention this upstream.

[Daniel van Vugt (vanvugt)]

As I am not aware of any bugs in the synaptics driver I think we should still call this a gnome-shell bug. It can stay open.