Changes

* with two more right-clicks you get another rectangle, and so on

* you can choose "Untrusted Ellipse (2 clicks)" or "Untrusted Quadrilateral (4 clicks)" and these work in exactly the same way

Unfortunately this interactive mode of establishing untrusted areas does not currently work well over a ssh (or NXclient) connection, probably because the lines/circles are re-drawn at high frequency. So it is recommended to run the program locally.