I was delighted to see the 'Guest Session' in the Power menu, top right of the screen.
When I click on Guest Session, MATE creates a 'temporary' session. When I try to open Firefox in the temporary session (from the Terminal) it gives me the following error:
cannot create user data directory: /tmp/guest-4z9pxi/snap/firefox/2277: Permission denied
I do like that the temporary session exists, however using firefox would be essential in the temporary session.
I presume this is to do with firefox being a snap perhaps. I really hope ubuntu \ MATE \ firefox move back to a PPA for the web browser. Or at least come up with a less intrusive snap solution to this new direction. [I understand that this is a sensitive \ controversial issue].