"chromium" runs as "slack" windows grouped together as Slack application

(EDIT: maybe this is a bug, and should go on GitHub.)

I just installed slack, then re-booted. Now, when I run Chromium, it shows up as Slack. Screenshot:

As you can see, I have only one window open, and it shows up as Slack.

Now because I have Chromium open, I can’t open the actual Slack app, because it thinks I already have Slack open.

So if I quit “Slack” (Chromium), then I start “Slack” instead of “Chromium”, then it’ll open the actual Slack app, but if I then open Chromium, it’ll open a new Chromium window still under Slack!

This screenshot shows both Slack and Chromium windows under “Slack” in the alt-backtick window switcher:

This screenshot shows both Chromium and Slack windows in the Activities overview, but as you see in the task bar there is only “Slack” running:

Looks like a similar issue here: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1766230

If you press alt-F2 and type lg Enter, you will wander behind the looking glass. There in the Windows tab, you can see wmClasses of windows and the desktop files they are associated with. Hopefully, this helps in debugging.

Thanks for that tip. I’ll look at what I can find.

On a related note, this is now also happening with VSCodium. Here’s screenshots showing Chromium running under the app VSCodium - URL Handler, and you can see that the Activities dock bar does not contain the Chromium icon, but two VSCodium icons:

I think this a packaging bug in NixOS. I haven’t don’t anything crazy, only:

environment.systemPackages = with pkgs; [
  slack
  chromium
];

so the expectation is for it to just work. If I discover anything, happy to make a PR to nixpkgs, but I’m not familiar with this part of the desktop system yet.