bug#68827: Possible solution

[Eli Zaretskii <eliz@gnu.org>]

> Date: Wed, 31 Jan 2024 20:56:12 +0100
> From: Gabriele Nicolardi <gabriele@medialab.sissa.it>
> 
> I checked the value of the font-lock-keywords variable and found: 
> 
> ```lang-el
> 
> ("\\\(ProvidesFile\|href\|nolinkurl\|path\|url\) \(\[[^]]\] \){\(\(?:[^{}\]\|\\.\|{[^}]}\)+\)" 3 'tex-verbatim t)
> 
> ```
> 
> If I use this command to add fontification:
> 
> ```lang-el
> 
> (font-lock-add-keywords nil '(("\\\(ProvidesFile\|href\|nolinkurl\|path\|url\) \(\[[^]]\] \){\(\(?:[^{}\]\|\\.\|{[^}]}\)+\)" 3
> 'tex-verbatim keep)))
> 
> ```
> 
> the problem disappears.
> 
> From the manual, I read:
> 
> The last two values in subexp-highlighter, override and laxmatch, are optional flags. If override is t, this
> element can override existing fontification made by previous elements of font-lock-keywords. If it is
> keep, then each character is fontified if it has not been fontified already by some other element. If it is
> prepend, the face specified by facespec is added to the beginning of the font-lock-face property. If it
> is append, the face is added to the end of the font-lock-face property. 
> 
> So I think that "keep" should be the right choice.

Stefan, any comments to this proposed solution?