I think that i discovered Processing 3 years ago, but i didn’t find your library because at that time i didn’t had any idea what a GUI was 
Anyway is your library “compatible” in python mode? I found this, but maybe the situation has changed https://forum.processing.org/two/discussion/21913/using-g4p-on-processing-py
P.S: if you accept a suggestion you should put an example of one GUI made with your library that has a few of your tools (check box, drop list, slider, ecc)