signal-desktop does not support fractional scaling on wayland

[cuu508]

Using a supported version?

• I have searched searched open and closed issues for duplicates.
• I am using Signal-Desktop as provided by the Signal team, not a 3rd-party package.

Overall summary

I am using Ubuntu 24.04, GNOME 46, Wayland windowing system, Intel integrated graphics.

I'm using fractional scaling with 150% scale.

I've installed signal-desktop 7.12.0 from Signal's apt repository. When I launch signal-desktop, the app runs and UI elements have reasonable size, but all of the UI slightly blurry.

There are tips floating around to use signal-desktop --enable-features=UseOzonePlatform --ozone-platform=wayland and also how to put together ~/.local/share/applications/signal-desktop.desktop with the same flags.

When I use this workaround I get sharp UI, but I also see several new issues:

• the app does not launch on the first launch (the process starts and outputs stuff to console, but no UI shows up). I have to start the second instance of the app for the UI window to appear
• the app uses a generic icon in the Alt+Tab dialog, and in the app overview (Win key)

Steps to reproduce

1. install signal-desktop on a system using GNOME, Wayland and fractional scaling
2. launch signal-desktop

Expected result

Sharp UI

Actual result

Blurry UI

Screenshots

Blurry UI (with GNOME Settings app on top for comparison):

Generic icon when using --enable-features=UseOzonePlatform --ozone-platform=wayland

Signal version

7.12.0

Operating system

Ubuntu 24.04

Version of Signal on your phone

No response

Link to debug log

No response

[trevor-signal]

@cuu508 can you run an Electron Fiddle and see if you can reproduce the issue? Thanks!

[cuu508]

I installed electron-fiddle_0.36.3_amd64.deb. Running it with no arguments, I get blurry UI (Electron Fiddle on top, GNOME Terminal below as comparison):

If I run it with --enable-features=UseOzonePlatform --ozone-platform=wayland arguments, I get sharp UI:

Unlike signal-desktop, the UI shows up on the first launch, and the app icon is correct in Alt+Tab and app overview views.

[trevor-signal]

@cuu508 thanks for that. The window not opening is a known issue; we're tracking it here: #6368.

[RelicCornhusk]

Same issue on Fedora Workstation 40 (wayland and using 150% fractional scaling). This seems to be an issue on flatpaks that don't support Wayland natively and rely on XWayland (source).

@cuu508 I managed to get rid of this issue by editing my signal-desktop flatpak to run with the following flags: --enable-features=UseOzonePlatform --ozone-platform=wayland. To do so, I had to edit /var/lib/flatpak/exports/share/applications/org.signal.Signal.desktop, more specifically the flatpak run command to include those flags. Not blurry anymore for me. (see #5719)

Really wish this was the default for Wayland environments until Wayland is not supported natively.

Update: It was becoming a nightmare updating these run options on a per-app basis so the temporary solution I've found is to tweak the scaling factor on gnome-tweaks to 1.25 and keep the resolution scale at 100% on gnome-settings. Apps are not blurry anymore.

[RayJW]

Same issue on Fedora Workstation 40 (wayland and using 150% fractional scaling). This seems to be an issue on flatpaks that don't support Wayland natively and rely on XWayland (source).

@cuu508 I managed to get rid of this issue by editing my signal-desktop flatpak to run with the following flags: --enable-features=UseOzonePlatform --ozone-platform=wayland. To do so, I had to edit /var/lib/flatpak/exports/share/applications/org.signal.Signal.desktop, more specifically the flatpak run command to include those flags. Not blurry anymore for me. (see #5719)

Really wish this was the default for Wayland environments until Wayland is not supported natively.

Update: It was becoming a nightmare updating these run options on a per-app basis so the temporary solution I've found is to tweak the scaling factor on gnome-tweaks to 1.25 and keep the resolution scale at 100% on gnome-settings. Apps are not blurry anymore.

The Flatpak maintainers already did all that work. This is from the Readme:

Wayland support can also be enabled on the command line:
flatpak override --user --env=SIGNAL_USE_WAYLAND=1 org.signal.Signal