@mschnell
Thanks for the precision!
@all
I put a minimal Python Tkinter template for ReaScript on ReaTeam Template repo, if you want to experiment:
ReaScripts-Templates/X-Raym_Basic tkinter python.py at master · ReaTeam/ReaScripts-Templates
You only need to add your own buttons,
Note that there is also several possible layout
GUI Programming with Python: Layout Management in Tkinter
Have fun!