Rated 4 out of 5 stars
Great and simple, as the equivalent old and vanished addon. Thanks for that.
A "No proxy" selection would indeed be nice.
Also, it would be nice if you could just replace (from configuration, as an option) the status bar text with a since icon. The text is helpful but takes too much space.
The "Proxy: System Proxy" could be just "Proxy: System" or perhaps "(System Proxy)". Respectively, "Proxy: None" or "(No Proxy)"