RE: [External] : Re: minor mode for highlighting character classes such as non-ascii (bug 47455)

[Drew Adams]

> > More useful is something like what library `highlight-chars.el'
> > offers.  You can highlight any chars you like, in any way you
> > like.  You can highlight arbitrary chars, chars in char ranges,
> > char classes, or charsets.
> 
> You mean, like highlight-regexp?

No.  I mean like what I linked to.  There you'll
find a succinct description.  I think you'll be
able to see a real difference from
`highlight-regexp' (`hi-lock-face-buffer').

https://www.emacswiki.org/emacs/ShowWhiteSpace*HighlightChars

And the Commentary in highlight-chars.el offers
quite a bit more detail.

https://www.emacswiki.org/emacs/download/highlight-chars.el

But yes, hi-lock.el offers some improvement over
the hard-coded behavior of `nobreak-char-display'
and `whitespace-mode'.