Multi-monitor window-snapping snaps to wrong display

[Alan Pope 🍺🐧🐱 🦄]

Summary:

Snapping a window to one side of the screen will often snap to the side of the wrong monitor.

Steps to reproduce:

1. Have two monitors arranged side by side
2. Open a new application window such as nautilus or a terminal
3a. Grab the right half of the title bar of the window and drag it to the left side of the right monitor. Don't let go
or
3b. Grab the left half of the title bar of the window and drag it to the right side of the left monitor. Don't let go
  - The orange window snapping guide will appear in the correct place
4. Let go of the mouse
  - The window will snap to the wrong monitor

It appears due to the amount of the window hanging over the separation gap between the displays, it will favour snapping to the wrong monitor.

Here's a video showing it: https://www.youtube.com/watch?v=bdJ6x9nnvOQ

ProblemType: Bug
DistroRelease: Ubuntu 20.10
Package: gnome-shell 3.38.1-1ubuntu1
ProcVersionSignature: Ubuntu 5.8.0-23.24-generic 5.8.14
Uname: Linux 5.8.0-23-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu50
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Thu Oct 22 09:40:58 2020
DisplayManager: gdm3
InstallationDate: Installed on 2020-08-15 (67 days ago)
InstallationMedia: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
RebootRequiredPkgs:
 linux-image-5.8.0-25-generic
 linux-base
 linux-base
RelatedPackageVersions: mutter-common 3.38.1-1ubuntu1
SourcePackage: gnome-shell
UpgradeStatus: Upgraded to groovy on 2020-09-20 (31 days ago)

[Daniel van Vugt (vanvugt)]

Sounds like bug 1900009, I hope.

[Alan Pope 🍺🐧🐱 🦄 (popey)]

It does indeed! Thanks.
Looks like upstream marked the linked bug from there as a dupe of https://gitlab.gnome.org/GNOME/mutter/-/issues/1389 which is the 'real' bug marked as fixed in https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1493