Re: Can watermarking Unicode text using invisible differences sneak through Emacs, or can Emacs detect it?

[Eli Zaretskii]

> Date: Wed, 19 Jan 2022 23:05:51 +1300
> From: Phil Sainty <psainty@orcon.net.nz>
> Cc: Richard Stallman <rms@gnu.org>, emacs-devel@gnu.org
> 
> On 2022-01-19 17:47, Po Lu wrote:
> > I think the "zero width characters" alluded to are displayed
> > by Emacs as 1 pixel wide spaces
> 
> You can highlight them like so:
> 
> (set-face-background 'glyphless-char "red")
> 
> I've had that configured ever since
> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=31194#40
> 
> If you're not expecting zero-width characters in text in general,
> I think it's a good setting.

Users and readers of certain scripts cannot use such a simplistic
solution, which is basically only suitable for plain ASCII text.  (And
even there it is slowly becoming inappropriate, what with the growing
popularity of ligatures, let alone Emoji.) Emacs should be able to do
better.