Fractional scaling window sizes incorrect after resume from suspend

[Michael Gratton]

LP bug as requested at https://gitlab.gnome.org/GNOME/mutter/issues/1122

From the summary there:

With fractional scaling enabled, after resume from suspend, maximised & half tiled windows have been resized/scaled so they are too large for the screen, and as a result no longer fit on the screen. Not sure if it also happens to windows that aren't in either of these states, I rarely have any. Further, most but not all windows are scaled like this. Epiphany and Terminal definitely are, maybe XWindows clients like Emacs aren't?

Under 3.34, shell/mutter seemed to notice this and would visibly snap the window sizes back to what they should be. Under 3.36, that no longer seems to happen - the windows stay too big and I need to manually fix them.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: mutter 3.35.91-1ubuntu1
ProcVersionSignature: Ubuntu 5.4.0-14.17-generic 5.4.18
Uname: Linux 5.4.0-14-generic x86_64
ApportVersion: 2.20.11-0ubuntu20
Architecture: amd64
CurrentDesktop: GNOME
Date: Fri Mar 20 16:54:48 2020
InstallationDate: Installed on 2018-08-13 (584 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
SourcePackage: mutter
UpgradeStatus: Upgraded to focal on 2020-03-07 (12 days ago)

[Kai-Heng Feng (kaihengfeng)]

Daniel,

I can bisect gnome-shell/mutter if there's a detailed instruction how do do that on Ubuntu.

[Daniel van Vugt (vanvugt)]

There isn't. And bisecting between gnome-shell and mutter is hard because they frequently break each other's dependencies as well as dependencies on other projects.

So do it at your own risk, but there are no instructions or scripts for that right now.

[Daniel van Vugt (vanvugt)]

Sounds like bug 1793496 might cover this. Let's see if that fix resolves it...

[Marco Trevisan (Treviño) (3v1n0)]

Is this happening only when suspending by closing the laptop lid?

[Michael Gratton (mjog)]

> Is this happening only when suspending by closing the laptop lid?

Just tried suspending from the menu a few times and it didn't happen at all, so perhaps.

[Kai-Heng Feng (kaihengfeng)]

The merge request doesn't fix the issue on my 200% scaled monitor.
It's a desktop so it doesn't have lid.

[Michael Gratton (mjog)]

After upgrading to 3.36.1-3ubuntu3, the issue seems to have been resolved on my laptop. This is with limited testing however, will report back over the next few days if I see it again.

[Daniel van Vugt (vanvugt)]

Can we get some confirmation this is really a fractional scaling issue?

On the affected machine, please run:

  gsettings get org.gnome.mutter experimental-features > experiments.txt
  xrandr --verbose > xrandr.txt

and then attach the resulting text files here, as well as a copy of:

  ~/.config/monitors.xml

[krul (krul)]

i experience same issue (on a desktop). Find attached the requested config files.

[Daniel van Vugt (vanvugt)]

Thanks krul, that confirms fractional scaling for you. I am still curious to also hear back from Michael Gratton.

[Daniel van Vugt (vanvugt)]

Also Michael logged this bug from a Wayland session.

[Michael Gratton (mjog)]

Nothing extra to report - haven't seen it again.

[Daniel van Vugt (vanvugt)]

In that case this bug should be closed and anyone like krul still experiencing issues, please open a new bug by running:

  ubuntu-bug mutter