Scaling of Firefox doesn't adjust when moved across Monitors with Different DPis

[Patrick Garraud]

Firefox doesn't automatically scale up/down when dragged across screens with different DPis like other apps and keeps the Scaling of the monitor it was opened on.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: firefox 83.0+build2-0ubuntu0.20.04.1
ProcVersionSignature: Ubuntu 5.4.0-54.60-generic 5.4.65
Uname: Linux 5.4.0-54-generic x86_64
AddonCompatCheckDisabled: False
ApportVersion: 2.20.11-0ubuntu27.12
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: patrick 1854 F.... pulseaudio
 /dev/snd/controlC0: patrick 1854 F.... pulseaudio
BuildID: 20201112153044
CasperMD5CheckResult: skip
Channel: Unavailable
CurrentDesktop: ubuntu:GNOME
Date: Mon Nov 23 18:40:44 2020
DefaultProfileExtensions: extensions.sqlite corrupt or missing
DefaultProfileIncompatibleExtensions: Unavailable (corrupt or non-existant compatibility.ini or extensions.sqlite)
DefaultProfileLocales: extensions.sqlite corrupt or missing
DefaultProfilePrefErrors: Unexpected character ',' before close parenthesis @ /usr/lib/firefox/omni.ja:greprefs.js:354
DefaultProfileThemes: extensions.sqlite corrupt or missing
ForcedLayersAccel: False
InstallationDate: Installed on 2020-11-18 (5 days ago)
InstallationMedia: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
IpRoute:
 default via 192.168.1.1 dev wlp2s0 proto dhcp metric 600
 169.254.0.0/16 dev wlp2s0 scope link metric 1000
 192.168.1.0/24 dev wlp2s0 proto kernel scope link src 192.168.1.11 metric 600
Profile0Extensions: extensions.sqlite corrupt or missing
Profile0IncompatibleExtensions: Unavailable (corrupt or non-existant compatibility.ini or extensions.sqlite)
Profile0Locales: extensions.sqlite corrupt or missing
Profile0PrefErrors: Unexpected character ',' before close parenthesis @ /usr/lib/firefox/omni.ja:greprefs.js:354
Profile0PrefSources: prefs.js
Profile0Themes: extensions.sqlite corrupt or missing
Profiles:
 Profile1 (Default) - LastVersion=None/None (Out of date)
 Profile0 - LastVersion=83.0/20201112153044 (In use)
RunningIncompatibleAddons: False
SourcePackage: firefox
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 07/09/2020
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.11.10
dmi.board.name: 02TH5P
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 31
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvr1.11.10:bd07/09/2020:svnDellInc.:pnPrecision55302-in-1:pvr:rvnDellInc.:rn02TH5P:rvrA00:cvnDellInc.:ct31:cvr:
dmi.product.family: Precision
dmi.product.name: Precision 5530 2-in-1
dmi.product.sku: 08AC
dmi.sys.vendor: Dell Inc.

[Olivier Tilloy (osomon)]

Thanks for the report Patrick.

Are we talking about scaling the webcontents, or the user interface (tabs bar, address bar, …), or both?

Can you test whether upstream firefox builds (which you can download from https://www.mozilla.org/firefox/download/thanks) are similarly affected?

I see that you're running in a Wayland session. Does this also affect Xorg sessions?

[Patrick Garraud (pgarraud)]

The scaling of both the Web Content and Navigation are affected, the problem still occurs in upstream Firefox, and Xorg doesn't support two monitors with different DPis.

[Olivier Tilloy (osomon)]

Thanks for the clarifications Patrick.
I couldn't find an upstream bug report for this issue, would you mind filing one at https://bugzilla.mozilla.org/enter_bug.cgi#h=dupes%7CFirefox and sharing the link to it here?
Thanks in advance.

[Patrick Garraud (pgarraud)]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0

Steps to reproduce:

Moved Firefox from a window with 100% scaling to one with 200% scaling or vice versa.

Actual results:

The window and Web contents retained the scaling from the original window

Expected results:

The window to automatically adjust to the scaling of the window it's in.

(Ubuntu Bug Report: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1905337)

[Release-mgmt-account-bot (release-mgmt-account-bot)]

[Bugbug](https://github.com/mozilla/bugbug/) thinks this bug should belong to this component, but please revert this change in case of error.

[Patrick Garraud (pgarraud)]

Link to bugzilla report.

https://bugzilla.mozilla.org/show_bug.cgi?id=1679335

[Olivier Tilloy (osomon)]

Thanks!

[Jmathies (jmathies)]

We have some reports that this is happening on Windows. We did some pretty exhaustive testing of scaling with multi-monitor system in the spring and didn't find anything, so maybe there's a recent regression.

[Jmathies (jmathies)]

Resetting things, and will file a fresh bug on the Windows issue.

[Stransky (stransky)]

X11 does not support it AFAIK. Please try Wayland desktop in Ubuntu 20.04 although the support is still not 100% perfect - there are some glitches when window is moved across monitors and popups are sometimes invisible - but that will be fixed.

[Patrick Garraud (pgarraud)]

(In reply to Martin Stránský [:stransky] (ni? me) from comment #4)
> X11 does not support it AFAIK. Please try Wayland desktop in Ubuntu 20.04 although the support is still not 100% perfect - there are some glitches when window is moved across monitors and popups are sometimes invisible - but that will be fixed.

This was tested in Wayland.

[Stransky (stransky)]

Good.
Can you please create a screencast of the issue?
https://help.gnome.org/users/gnome-help/stable/screen-shot-record.html
(the screencast records all monitor so it will be visible there)
Thanks.

[Patrick Garraud (pgarraud)]

Created attachment 9233014
Firefox Scaling Issue

[Stransky (stransky)]

So you have primary screen with 200% scale, secondary with 100% scale, right?
Please

1) attach content of about:support page.
2) run Firefox with MOZ_LOG="Widget:5" env variable and attach the log here.

Looks Firefox does not get 'scale change' event.
Thanks.

[Patrick Garraud (pgarraud)]

Created attachment 9233119
About Support Page

[Stransky (stransky)]

Yes, scaling is not supported on X11. You need to use Wayland backend for it.