Re: How to add syntax-highlighting to a Help buffer?

[Michael Heerdegen]

Raffaele Ricciardi <rfflrccrd@gmail.com> writes:

> (font-lock-add-keywords
>  nil
>  `(("\\(arbitrary regexp\\)" 1 'font-lock-function-name-face)))
>
> But the above expression breaks the existing highlighting (the
> highlighting of the function arguments disappears).

AFAICT you experience a normal "feature" of font-lock-mode.

help-mode doesn't use font-lock.  It directly attaches face text
properties to the buffer text.  If font-lock-mode fontifies such a
buffer (it doesn't as long as font-lock-keywords is nil even when it is
active), all face text properties get ignored by the display engine.
Note that there is a font-lock-face text property existing as well.

hi-lock works in this case because it handles that case specially and
uses overlays.


HTH,

Michael.