Programs are grouped with the program that launched them. How can I change that?

Question

This morning, I launched Slack from the program list. Once it was up and running, I clicked a link therein, which launched Firefox. In fact, it launched four Firefox windows, each with many tabs, because Firefox remembers my previous session, and I'm disorganized like that.

However, in the program switcher (Alt+Tab), the Firefox windows are bundled in with the Slack window. So too in the launcher bar, where the Firefox icon shows with no dots underneath, and the Slack icon with five. I visited about:profiles in Firefox and restarted the program, but it’s still associated with Slack.

I often start Firefox by clicking a link in an email, but I’ve never had it grouped in with Thunderbird. I often start Slack from Firefox, by opening the Slack webapp, and selecting the “Open the Slack App” option therein. This sometimes causes Slack to be grouped within the Firefox windows (the opposite of what I have today).

I find this somewhat irritating. Is there an easy way to fix it? Should I be reporting this as a bug instead of / as well as asking about it here?

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 18.04.3 LTS
Release:    18.04
Codename:   bionic

Answer 1

If your apps are installed via snap, that could be the problem.

I had a similar issue and turned out to be caused by the way snaps work. They have their 'own environment' and sometimes they do not have access to other processes, that's why other apps launched from within the snap are under its name/process.

The simplest solution I could find was to install the programs some other way (.deb files or apt).

Edit: Answering your question from the comments (I can't comment yet as I don't have enough reputation):

.desktop files can be found in /usr/share/applications (all users) and ~/.local/share/applications (current user)