Re: [External] : Re: Strange whitespaces.

[Hongyi Zhao]

On Thu, Sep 30, 2021 at 11:20 PM Drew Adams <drew.adams@oracle.com> wrote:
>
> > Why are both displayed as red underscores in Emacs?
>
> I don't think the EN SPACE is displayed that way.
> Not with `emacs -Q' (no init file), at least.  But
> I don't have an Emacs 28 prerelease build - maybe
> they changed Emacs 28 to highlight that as well.
>
> As for a NO-BREAK SPACE, it's highlighted (with face
> `nobreak-space', which inherits from `escape-glyph')
> if variable `nobreak-char-display' is non-nil, which
> it is by default.
> ___
>
> Note that `nobreak-char-display' highlights all
> no-break (aka "hard") characters, not just the
> no-break space.  IOW, it highlights hard hyphens
> (code point 8209) as well as hard spaces.

What's the meaning of "hard" here?

> Vanilla Emacs doesn't let you highlight these
> chars differently (e.g. highlight only hard spaces
> or only hard hyphens.  (This highlighting
> is low-level - it doesn't use Font Lock mode.)
>
> But you can highlight such chars differently, or
> highlight only one of them, using library
> `highlight-chars.el'.
>
> https://www.emacswiki.org/emacs/ShowWhiteSpace#HighlightChars

Thank you for telling me about it.

HZ