how is dock, panel, launcher thingy configured

[bitrat2]

Hi,

stuff appears on the launcher when I run it and sometimes it doesn't and sometimes I can right click and add to favourites and sometimes I can't and sometimes a snap adds itself to the dock and sometimes it doesn't, and sometimes I run an app image and the dock doesn't distinguish between that app and the same app run from snap, and usually I can't find the .desktop file relating to an app on the dock and sometimes I want access to that file because I want to modify, for example the command line used to run that app, and sometimes I'd just like to have an icon on the launcher that is just a directory opened by nautilus, or a bash script, or whatever, or sometimes I just want to change the icon colour..

I've found I can add my own shortcuts to .local/share/applications/something.desktop but I don't see much rhyme or reason in the stuff that happens automatically.For example, I added my own desktop file to run firefox with a different profile, and this worked fine for a while, but now the icon still runs the app, but the running app and it's windows appear under the default firefox icon. I imagine something is overriding something, somewhere, possibly as a result of an update, but I really can't be bothered spelunking the mechanism without a better understanding of the wider context...

I'm probably not paying attention, but how does this thing work? How do apps add and remove themselves, what happens when they're added and removed from favourites, how can I intervene in the default actions and/or add and remove apps manually? Where should they be configured, ideally, for individual users and globally.

Any further enlightenment would be appreciated!

Cheers,
bitrat