> But that will not work as expected if you have more than one profile (which is the whole point). At present the only workable solution is to fiddle with a GUI thru `about:profiles` (or `firefox --ProfileManager`) in order to create the profiles and give them all-important UIDs.

FWIW, that's only true if you care about it having those IDs and being exposed to the graphical interface. If you don't, then you can just run `firefox --profile $HOME/.mozilla/firefox/whatever` and it works. I use a small shell script™ wrapper to run firefox this way and it's quite nice. Also helpful: If you run firefox like that, you can just point it at a new empty directory and it'll populate it as a profile, so it's easy to make new ones too.

But that script won't work if you need to open subsequent new windows in particular profiles.

PS: probably. It's possible there was a fix. The GUI setup remains unscriptable.