Re: Behavior of evaporate

[Richard Stallman]

    Yes.  From the manual:

    `evaporate'
         If this property is non-`nil', the overlay is deleted automatically
         if it ever becomes empty (i.e., if it spans no characters).

    But the overlay does not become empty in your example.  It _is_
    already empty.

I clarified the manual as follows:

@item evaporate
@kindex evaporate @r{(overlay property)}
If this property is address@hidden, the overlay is deleted automatically
if it becomes empty (i.e., if its length becomes zero).  However,
if the overlay is @emph{already} empty, @code{evaporate} does not
delete it.

Is that entirely correct?

Also, is that really what we want?  Maybe setting the `evaporate'
property non-nil should delete the overlay immediately if it is
already empty.  That would be more consistent.