Interactive Python Shell in NS-3 PyViz

With ns-3-pyviz, one of my patterns of debugging simulations was to run "ipython -gthread myscript.py". This would run the gtk main loop in a thread and allow me to interact with the IPython shell and inspect a live simulation, to find out what is going on.

Since ipython -gthread stopped working in recent versions, I decided to just follow a recipe for embedding an IPython shell into an existing pygtk program. It has been pretty easy to do, thanks to reusing the work of others (Eitan Isaacson, in this case); thank you, open source! :-)