Background: I use Firefox in GNOME 3. Running one instance works fine, but running a second one (for example stable and aurora, or two separate profiles) is tricky: in order to not break the window management in gnome-shell, you need to create a second .desktop file and use --class=foo to match WM_CLASS and .desktop file name. This works fine as long as the browser does not restart, which unfortunately happens sooner or later: - after enabling/disabling some extensions - after applying updates - after a crash When such a restart is triggered, the WM_CLASS is the default one ("Firefox"), it does no longer set the WM_CLASS you requested using --class. Is there a way to apply this class also after restarts? This would solve the problem I think. Anyway I think it would be helpful to not use "Firefox" for all Firefox build channels and also use different executable names for each one.

I think this was resolved recently. Custom window class is kept after restarts on Nightly 59.

No, still not working for me, it restarts with a different wm_class after updates.

Works for me with Nightly 59.0a1 (2017-12-29) on Ubuntu 17.10 using GNOME Shell (Xorg).

(In reply to Kestrel from comment #4) > Works for me with Nightly 59.0a1 (2017-12-29) on Ubuntu 17.10 using GNOME > Shell (Xorg). Yeah, not working on Wayland.

Can confirm it does not work on Wayland.

> Anyway I think it would be helpful to not use "Firefox" for all Firefox build channels and also use different executable names for each one. Yes, totally! Maybe better create a new bug for this, though as it could get lost in this one?