Some people use Windows Explorer as their default means for working with programs and files, including Python via Idle and their own .py files. What some need, as I said previously, is an explicit 'Edit with Idle x.y' for each installed Python.  They need this for the same reason that we add a separate directory to the Start Menu for each version, and not just one Python directory.  If you want me to take this request to pydev, I will, but it seems straightforward to me.

For 3.x, '-m idlelib' is sufficient, '.idle' is not needed (at least from the Windows command line).  I just verified that that 'py -3 -m idlelib path' opens path in a 3.5.0a2 Idle editor.

The fact that installing the experimental -- and broken for Idle -- alpha as non-default changes the behavior of the above incantation illustrates why separate context menu entries are needed, and why the associated command should be 'py -x.y -m idlelib %1'.

(Yes, the only option recognized by py.exe is a version option.  Anything after, like -m, is an option either for the python that py runs or the program that python runs.  '-m module' is equivalent to a .py file, so anything after that is am option for the module being run as a program.)