Multi monitor with different scale factors causes windows to use scale factor of adjacent monitor before arriving at boundary

[Umayr Saghir]

On a dual/multi monitor setup, if the monitor adjacent uses a different scale factor, when moving an application window to the boundary the application will change its scaling just slightly before the actual apparent window starts crossing over. Taking a look at looking glass shows the transition occurs when the MetaSurfaceActorWayland region (larger than the actual window) meets the boundary.

My monitor configuration is:
1920X1080 monitor using 100% scaling
2560X1600 monitor using 150% scaling

ProblemType: Bug
DistroRelease: Ubuntu 23.10
Package: gnome-shell 45.0-1ubuntu1
ProcVersionSignature: Ubuntu 6.5.0-5.5-generic 6.5.0
Uname: Linux 6.5.0-5-generic x86_64
ApportVersion: 2.27.0-0ubuntu2
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Sat Sep 23 00:22:04 2023
DisplayManager: gdm3
InstallationDate: Installed on 2022-03-31 (540 days ago)
InstallationMedia: Ubuntu 22.04 LTS "Jammy Jellyfish" - Beta amd64 (20220329.1)
RelatedPackageVersions: mutter-common 45.0-1ubuntu1
SourcePackage: gnome-shell
UpgradeStatus: No upgrade log present (probably fresh install)

[Umayr Saghir (nightmayr)]

Screenshot of the looking glass inspector being used to on application window at the point where the scaling changes.

[Launchpad Janitor (janitor)]

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

[Daniel van Vugt (vanvugt)]

This is because the Wayland surface includes the window shadows which go out to the edge of the red rectangle. It's an understandable bug but could always be better.