Some apps appear blurry with framebuffer scaling

[Wolf Rogner]

Microsoft VScode bug: https://github.com/Microsoft/vscode/issues/72759
Chromium bug?: https://bugs.chromium.org/p/chromium/issues/detail?id=578890

Setting the framebuffer scaling (with gsettings set org.gnome.mutter experimental-features "['scale-monitor-framebuffer']") allows the display on HiDPi to be scaled to something different than 100%/200%/300%.

Which would be fine.

However, the display is rendered such that most applications provide blurred display of text and graphics.

This is not always the case (e.g. system settings are displayed correctly, Thunderbird and Firefox are blurred).

Also the screen flickers when selection menus or resizing the windows.
A black border appears around the windows where the shadow should appear. It gets removed a few seconds later but still is irritating.

This issue is not urgent, just annoying. It can be worked around by removing the settings in gsetting / dconf.

ProblemType: Bug
DistroRelease: Ubuntu 19.04
Package: mutter 3.32.0+git20190410-1ubuntu1
ProcVersionSignature: Ubuntu 5.0.0-13.14-generic 5.0.6
Uname: Linux 5.0.0-13-generic x86_64
ApportVersion: 2.20.10-0ubuntu27
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Sat Apr 20 11:11:55 2019
InstallationDate: Installed on 2018-04-30 (355 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
SourcePackage: mutter
UpgradeStatus: Upgraded to disco on 2019-04-19 (0 days ago)

[Daniel van Vugt (vanvugt)]

Actually, this might not be the problem I was imagining...

Could you please attach a screenshot or photo of the problem you are describing?

[Wolf Rogner (war-rsb)]

With framebuffer scaling some applications (e.g. the settings app) do work fine. Others don't (e.g. Firefox, but also LibreOffice)

[Daniel van Vugt (vanvugt)]

Thanks!

The blurriness in comment #4 is expected. Any apps which don't natively support scaling will be scaled by the compositor, which means they will either appear blurry or unevenly pixelated. We choose blurry. So this is not a mutter or gnome-shell bug. It is however a Firefox bug for not supporting scaling.

As for the black frame in comment #5, that is a different issue. That is bug 1751593.

[Wolf Rogner (war-rsb)]

Re #7: 90% of the applications experience this and that should be normal? Huhh.
Re #8: Fix released? So it could be fixed? What was the issue? How do we get the fix?

[Daniel van Vugt (vanvugt)]

Ignore the "Fix Released" comment. It is a mistake in the bug tracker. The upstream bug was closed because it was rejected, not fixed (https://gitlab.gnome.org/GNOME/mutter/issues/566).

[Launchpad Janitor (janitor)]

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

[Daniel van Vugt (vanvugt)]

Despite what I said in comment #7 I also now have a partial fix proposed:
https://gitlab.gnome.org/GNOME/mutter/merge_requests/845

[Daniel van Vugt (vanvugt)]

My proposed branch (for integer scaling cases) was closed in favor of

https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1124

which is in mutter 3.36.1 already.