Third revision.

 - Addressed Stefan's nit.
 - Extended the large comment.
 - Switched to Stefan's suggestion for calc.
 - Added a NEWS item that describes the suggestion
 - Added a commit that removes the Microsoft hack

> > It might be worth mentioning that the main difference is the
> > availability of `executing-kbd-macro` to let ELisp code behave
> > differently when called via a kmacro than via "live input".
> > Which also kind of justifies why `read-key-sequence` wants to
> > detect the end: if a kmacro ends in the middle of a key sequence,
> > then
> > it's triggered both my kmacro and by live input.
> > [ Of course, we could handle it in the command loop instead:
> >   check and compare the set of pending kmacro events before and
> > after
> > we
> >   call `read-key-sequence`.  ]

I didn't do this, because I couldn't follow exactly what you're saying.
Feel free to suggest a sentence.

Best,
Tim