Just a quick note.
I'd written earlier about setting the Gnome Shell session status to "busy". The post documented how it could be done from the terminal. We'd been discussing this on the Fedora Workstation mailing list and one of the subscribers there, Norman, went ahead and wrote an extension already! I tried it out already and it works really well. You can get it here from the Gnome Shell extensions page.
It adds a button to the top panel that toggles the session status between "Active" and "Busy".