bug#5122: Mismatched parentheses when dealing with huge buffercontent

[Drew Adams]

> > It's not real obvious when you see mismatch highlighting 
> (and are used to it
> > working) that the highlighting might not mean a mismatch at 
> all, but just an
> > insufficiently large option value. Many (most?) users will 
> not even guess that
> > there is such an option.
> > 
> > Perhaps we could use a :help-echo property along with the 
> mismatch highlight
> > face, pointing to the option?
> 
> help-echo is not guaranteed to be seen, and could be tricky when
> there's an important message in the echo area (especially if the
> help-echo itself is displayed in the echo area).  Also, it will not
> work on a text terminal.
> 
> I think it's better to modify the echo area message, such that if
> Emacs hits the blink-matching-paren-distance limit (as opposed to
> hitting point-min), the message says something like
> 
>   Mismatched parentheses (within blink-matching-paren-distance)

Yes that sounds good too.

To be honest, I don't know if I ever noticed any message in the echo area for
this. Perhaps because the message was so expected I never paid any attention to
it.