the code itself is pretty easy, what is difficult is keeping the interface clean between the dialog, the client and the server...

Maybe define a list of options for each session type? Is this too generic for the sake of it?

This used to be done with python-xlib code in window_util but was removed as it caused segfaults. r1450 All the other approaches I have tried did not work as advertised (root window property, etc..)

There must be something in dbus that would do the job, but I can't find it documented anywhere.

at present, a random port is chosen, which will not work with hosts running almost any kind of firewall...

Should re-use the spec parsing code used by the server, which supports syntax like:

=:2345
=127.0.0.1:
=192.168.0.1:2345,192.168.1.1:4567

etc