pyFLTK

mrv2 supports FLTK in python through the pyFLTK module. You can import it like:

from fltk14 import *

Once with it, you can create new windows, buttons, and any sort of other widgets the pyFLTK supports. For some demos, look into:

python/demos/fltk

For information about FLTK and pyFLTK (albeit the older 1.3), go to:

https://fltk.gitlab.io/fltk/

https://pyfltk.sourceforge.io/docs/CH0_Preface.html