Public bug reported:
Environment details:
OS: Ubuntu 26.10
GNOME Version: GNOME 51 (Wayland session)
Hardware: ASUS ProArt P16 H7606WV (Dual Graphics: AMD Radeon 890M iGPU /
NVIDIA dGPU)
GPU Driver: Mesa / radeonsi (DRM 3.64)
Description:
When running a Wayland session on a high-DPI display with fractional
scaling set to 150% or all non-integer / odd fractional scales, a
single-pixel black border rendering artifacts appear on the left side of
GTK context menus and at the top edge of GTK/Libadwaita window header
bars.
Steps to Reproduce:
Open Display Settings on a Wayland session under Ubuntu 26.10.
Set display scaling to 150%.
Open any native GTK window or right-click to open a context menu.
Observe thin black 1px border artifacts on menu/header edges.
Expected Result:
Sub-surfaces, shadows, and popups should render cleanly without border
pixel bleeding or sub-pixel coordinate rounding gaps.
Actual Result:
Floating-point coordinate rounding in Mutter causes single-pixel dark
line artifacts along window margins and popup edges.
Workaround / Verification Notes:
Changing display scale to an integer value (100% or 200%) completely
eliminates the issue.
Forcing xwayland-scaling-factor does not resolve it, indicating a native
Wayland surface calculation issue in Mutter.
Global text scaling factor is not a viable alternative due to layout
alignment regressions in Libadwaita.
ProblemType: Bug
DistroRelease: Ubuntu 26.10
Package: mutter (not installed)
ProcVersionSignature: Ubuntu 7.3.0-9.9-generic 7.3.0-rc6
Uname: Linux 7.3.0-9-generic x86_64
ApportVersion: 2.36.0-0ubuntu1
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Wed Oct 28 09:52:44 2026
InstallationDate: Installed on 2026-03-06 (236 days ago)
InstallationMedia: Ubuntu 25.10 "Questing Quokka" - Release amd64 (20251007)
ProcEnviron:
LANG=en_US.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
SourcePackage: mutter
UpgradeStatus: Upgraded to stonking on 2026-09-09 (49 days ago)
** Affects: mutter (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug stonking wayland-session
** Summary changed:
- [Fractional Scaling] Single-pixel black border artifact on GTK context menus
and window headers at 150% scale
+ [Fractional Scaling] Single-pixel black border artifact on GTK context menus
and window headers at 150%, 166% scale
** Description changed:
Environment details:
OS: Ubuntu 26.10
GNOME Version: GNOME 51 (Wayland session)
Hardware: ASUS ProArt P16 H7606WV (Dual Graphics: AMD Radeon 890M iGPU /
NVIDIA dGPU)
GPU Driver: Mesa / radeonsi (DRM 3.64)
Description:
When running a Wayland session on a high-DPI display with fractional
- scaling set to 150%, single-pixel black border rendering artifacts
- appear on the left side of GTK context menus and at the top edge of
- GTK/Libadwaita window header bars.
+ scaling set to 150% or odd % single-pixel black border rendering
+ artifacts appear on the left side of GTK context menus and at the top
+ edge of GTK/Libadwaita window header bars.
Steps to Reproduce:
Open Display Settings on a Wayland session under Ubuntu 26.10.
Set display scaling to 150%.
Open any native GTK window or right-click to open a context menu.
Observe thin black 1px border artifacts on menu/header edges.
Expected Result:
Sub-surfaces, shadows, and popups should render cleanly without border
pixel bleeding or sub-pixel coordinate rounding gaps.
Actual Result:
Floating-point coordinate rounding in Mutter causes single-pixel dark
line artifacts along window margins and popup edges.
Workaround / Verification Notes:
Changing display scale to an integer value (100% or 200%) completely
eliminates the issue.
Forcing xwayland-scaling-factor does not resolve it, indicating a native
Wayland surface calculation issue in Mutter.
Global text scaling factor is not a viable alternative due to layout
alignment regressions in Libadwaita.
ProblemType: Bug
DistroRelease: Ubuntu 26.10
Package: mutter (not installed)
ProcVersionSignature: Ubuntu 7.3.0-9.9-generic 7.3.0-rc6
Uname: Linux 7.3.0-9-generic x86_64
ApportVersion: 2.36.0-0ubuntu1
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Wed Oct 28 09:52:44 2026
InstallationDate: Installed on 2026-03-06 (236 days ago)
InstallationMedia: Ubuntu 25.10 "Questing Quokka" - Release amd64 (20251007)
ProcEnviron:
- LANG=en_US.UTF-8
- PATH=(custom, no user)
- SHELL=/bin/bash
- TERM=xterm-256color
- XDG_RUNTIME_DIR=<set>
+ LANG=en_US.UTF-8
+ PATH=(custom, no user)
+ SHELL=/bin/bash
+ TERM=xterm-256color
+ XDG_RUNTIME_DIR=<set>
SourcePackage: mutter
UpgradeStatus: Upgraded to stonking on 2026-09-09 (49 days ago)
** Summary changed:
- [Fractional Scaling] Single-pixel black border artifact on GTK context menus
and window headers at 150%, 166% scale
+ [Fractional Scaling] Single-pixel black border artifact on GTK context menus
and window headers at 150%(all non integar scales.
** Summary changed:
- [Fractional Scaling] Single-pixel black border artifact on GTK context menus
and window headers at 150%(all non integar scales.
+ [Fractional Scaling] Single-pixel black border artifact on GTK context menus
and window headers at 150%(all non integar scales).
** Description changed:
Environment details:
OS: Ubuntu 26.10
GNOME Version: GNOME 51 (Wayland session)
Hardware: ASUS ProArt P16 H7606WV (Dual Graphics: AMD Radeon 890M iGPU /
NVIDIA dGPU)
GPU Driver: Mesa / radeonsi (DRM 3.64)
Description:
When running a Wayland session on a high-DPI display with fractional
- scaling set to 150% or odd % single-pixel black border rendering
- artifacts appear on the left side of GTK context menus and at the top
- edge of GTK/Libadwaita window header bars.
+ scaling set to 150% or all non-integer / odd fractional scales, a
+ single-pixel black border rendering artifacts appear on the left side of
+ GTK context menus and at the top edge of GTK/Libadwaita window header
+ bars.
Steps to Reproduce:
Open Display Settings on a Wayland session under Ubuntu 26.10.
Set display scaling to 150%.
Open any native GTK window or right-click to open a context menu.
Observe thin black 1px border artifacts on menu/header edges.
Expected Result:
Sub-surfaces, shadows, and popups should render cleanly without border
pixel bleeding or sub-pixel coordinate rounding gaps.
Actual Result:
Floating-point coordinate rounding in Mutter causes single-pixel dark
line artifacts along window margins and popup edges.
Workaround / Verification Notes:
Changing display scale to an integer value (100% or 200%) completely
eliminates the issue.
Forcing xwayland-scaling-factor does not resolve it, indicating a native
Wayland surface calculation issue in Mutter.
Global text scaling factor is not a viable alternative due to layout
alignment regressions in Libadwaita.
ProblemType: Bug
DistroRelease: Ubuntu 26.10
Package: mutter (not installed)
ProcVersionSignature: Ubuntu 7.3.0-9.9-generic 7.3.0-rc6
Uname: Linux 7.3.0-9-generic x86_64
ApportVersion: 2.36.0-0ubuntu1
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Wed Oct 28 09:52:44 2026
InstallationDate: Installed on 2026-03-06 (236 days ago)
InstallationMedia: Ubuntu 25.10 "Questing Quokka" - Release amd64 (20251007)
ProcEnviron:
LANG=en_US.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
SourcePackage: mutter
UpgradeStatus: Upgraded to stonking on 2026-09-09 (49 days ago)
** Summary changed:
- [Fractional Scaling] Single-pixel black border artifact on GTK context menus
and window headers at 150%(all non integar scales).
+ [Fractional Scaling] Single-pixel black border artifact on GTK context menus
and window headers at 150%(all non integer scales).
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2172379
Title:
[Fractional Scaling] Single-pixel black border artifact on GTK context
menus and window headers at 150%(all non integer scales).
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/2172379/+subscriptions
--
ubuntu-bugs mailing list
[email protected]
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
