Is there a shortcut to switch back? Obviously once the window is frameless, I can't use the toolbar. Ty!

Very easy use
In the futur, it will be possible to get Fullscreen function ?
Thanks

Works fine, but compared to the Google Chrome extension, there's one drawback: I'm prevented from maximizing the frameless window. I use this all the time to switch a Google Meet conference from a small "camera only" view to the full view and back (e.g. to view or use the the meeting chat occasionally).

With WatsApp...

I use this add-on everyday. This is. currently, the only add-on I know of that will 'app-ify' stuff in Firefox.