i thought I may just give this question a try here. I’m using a patched version of Thunderbird called Betterbird which adds some useful features. Yesterday they’ve added systray support for new emails. Hey are using libayatana-appindicator. From my understanding this should easily work with the enabled AppIndicator/KStatusNotifierItem support for GNOME Shell extension.
Somehow the tray icon does not show up when running as normal user. It only does so when running the program as root. Seems like it’s a Gnome thing somehow as it seems to work with Cinnamon and KDE. If someone has an idea I’d be really happy
Both libayatana-appindicator and libappindicator-gtk3 work fine with gnome-shell-extension-appindicator. Note that neither work with Gtk 4 applications. However, there’s another implementation that Nicotine+ uses that does work.
It seems upstream may have already fixed it. Did you see the latest reply in the issue you linked?
FYI, Betterbird is available in the AUR (Arch User Repository) as a binary package: betterbird-bin.