RE: Revamping sit-for [Was: Lingering input pending with motif menu bar]

[Drew Adams]

    3. Put a new function `sit-for' in subr.el:

Excuse me if I'm misunderstanding, but how can you change the signature of
sit-for in a way that breaks existing code? IIUC, it is changing from

  (sit-for seconds)
  (sit-for seconds milliseconds)
  (sit-for seconds milliseconds nodisp)

to

  (sit-for seconds)
  (sit-for seconds nodisp)
  (sit-for seconds nodisp obsolete)

That means that existing calls that use the milliseconds arg will be newly
interpreted to consider that arg as a no-display arg, no?

What happens to an existing call such as (sit-for 3 200)? Is that now
interpreted as "sit for 3 seconds with no redisplay"? What about (sit-for 3
200 t) - is that too interpreted only as "sit for 3 seconds with no
redisplay"?

I didn't check the code; I just read the doc string.

    (defun sit-for (seconds &optional nodisp obsolete)
...
    An obsolete but still supported form is
    \(sit-for SECONDS &optional MILLISECONDS NODISP)
    Where the optional arg MILLISECONDS specifies an additional wait period,
    in milliseconds; this was useful when Emacs was built without
    floating point support.
    usage: (sit-for SECONDS &optional NODISP OLD-NODISP)"