Thank you but I can't seem to find the 'Popup Node' in 2016. There are only a 'Pop Back' & 'Pop Front' which, I don't believe, have anything to do with a popup window.
... Ok so I took a random node and erased all the python code. I then retyped all the code you posted above, recompiled it and i got it to work.
I still can't find the 'Popup Node' in 2016 and there doesn't seem to be an easy way to search for a specific node by name. I hope they have changed that in the newer versions.
Thank you for posting your reply, I really appreciate it because it now gives me the ability to interact with marionette on a whole new level.