Using Signal as the messenger of your choice is always a good idea. It provides State-of-the-art end-to-end encryption, Text-, Voice- and Video-Chats. You can chat 1:1 or in Groups. There are no adds in and it is always free for everyone. And finally it provides a desktop client for the main desktop OSes (Windows, OSX and Linux).
Unfortunately Signal Desktop app on Gnome (Fedora 38) does not facilitate hunspell, aspell or comparable and it does not support setup of spellcheck langues via its UI. So we need to find another solution for getting more than your default desktop locale as a spell checking language setted up.
This guide expect that you have installed Signal Desktop from flatpak but It should work with other kinds of installing. Probably you need to adapt other files but you need to find out on your own, please refer to the documentation of your distribution.
Language selection
Signal takes advantage of the local environment variables to determine the language for UI and/or spell checking.
To use the variable of the highest precedence you can configure LANGUAGE with your prefered language. It will setup the UI language as well the language used for spell checking.
To start Signal with the desired Language setting you can use env which sets up the environment for a process.
env LANGUAGE=de_DE /usr/bin/flatpak run org.signal.Signal
Multiple language support
As Signal uses get_language_names function from GLib it is possible to define more than one language to be used.
To define multiple, different languages you need to separate each other by a colon. E.g.
LANGUAGE=en_US:de_DE:it_IT
Note: The first locale from you language list will be determined as the UI language.
Setup Language selection
As you don’t want to start the app everytime from command line you need to setup your own desktop file. Simply copy the original startup file.
cp /var/lib/flatpak/app/org.signal.Signal/current/active/export/share/applications/org.signal.Signal.desktop .local/share/applications/
And adapt it to meet your needs, in my case I setup English, German and Italian for spell checking.
[Desktop Entry]
Name=Signal
Exec=env LANGUAGE=en_US:de_DE:it_IT /usr/bin/flatpak run --branch=stable --arch=x86_64 --command=signal-desktop --file-forwarding org.signal.Signal @@u %U @@
Terminal=false
Type=Application
Icon=org.signal.Signal
StartupWMClass=Signal
Comment=Private messaging from your desktop
MimeType=x-scheme-handler/sgnl;x-scheme-handler/signalcaptcha;
Categories=Network;InstantMessaging;Chat;
X-Desktop-File-Install-Version=0.26
X-Flatpak-RenamedFrom=signal-desktop.desktop;
X-Flatpak=org.signal.Signal
Apply language settings
If Signal was already running you need to restart it once. From this moment on your language settings will apply on each and every start of Signal Desktop.