What framework to select for application

[RobertIonescu]

Use .kv file to build the GUI and the program logic put into the .py file. That way you may change the program's interface anytime you need without risk to broke the program.

Yep that is also the way that the official kivy docs are proposing if the app is getting more complex than "hello world" :)
But it's still a bit hard to write the GUI in this kind of .kv style , i think this will be a real challenge for me until I am satisfied with the result