Robin2:
More recently I have been making my GUIs so they are viewed in a browser. I find it much easier to create screens with HTML and CSS. I use the Python Bottle web framework to create the server that produces the GUI stuff and works with Python code to talk to the Arduino.
Having done a little bit of web design long long ago, i have to ask if you ever run into browser compatibility issues. Like something that works on chrome but crashes on firefox or something like that. That's always been my fear of doing anything in a browser window.