Re: Question: add-face-text-property for 'font-lock-face?

[Clément Pit-Claudel]

On 8/29/21 12:13 AM, Qiantan Hong wrote:
> Users of crdt.el report that crdt-visualize-author-mode (which use 
> font-lock-face to color code author of texts)
> conflict with faces from other modes. Apparently there are more than 1 mode 
> which sets this text property.
> 
> Is there some way to add-face-text-property to 'font-lock-face property, 
> i.e. adding new face attributes instead of overwriting any existing face?
> add-face-text-property doesn’t seem to work because 'font-lock-face will just 
> override ‘face.

You want font-lock-append-text-property, I think:

  (font-lock-append-text-property START END PROP VALUE &optional OBJECT)

  Append to one property of the text from START to END.
  Arguments PROP and VALUE specify the property and value to append to the value
  already in place.  The resulting property values are always lists.
  Optional argument OBJECT is the string or buffer containing the text.