i tried in Control Panel\Programs\Default Programs\Set Associations, and also assoc/ftype, but windows keeps using the wrong python.exe (C:\Python27\) instead of the one i want (C:\Users\nlab\Downloads\WinPython-64bit-2.7.9.5\python-2.7.9.amd64\)
>where python
C:\Users\nlab\Downloads\WinPython-64bit-2.7.9.5\python-2.7.9.amd64\python.exe
C:\Python27\python.exe
C:\Program Files (x86)\LilyPond\usr\bin\python.exe
>assoc .py
.py=Python.File.WinPython
>ftype Python.File.WinPython
Python.File.WinPython=C:\Users\nlab\Downloads\WinPython-64bit-2.7.9.5\python-2.7
.9.amd64\python.exe "%1" %*
>set PATH
Path=C:\Users\nlab\Downloads\WinPython-64bit-2.7.9.5\python-2.7.9.amd64;...C:\Python27;C:\Python27\Scripts;...C:\Program Files (x86)\LilyPond\usr\bin;...
PATHEXT=.PY;...
i just made up Python.File.WinPython, is that allowed?