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

[Stefan Monnier]

> its author. The naive way that create an overlay for each character
> clearly doesn’t work (text property however works, because Emacs itself
> always merge them). We would need to look at overlays around the insertion
> point and opportunistically merge them.

IIRC we have pretty much exactly that need in outline.el where we use
overlays to put an `invisible` property.  See `outline-flag-region`.
AFAICT this code currently doesn't try and merge overlays upon
insertion, but it shouldn't be hard to add that functionality.


        Stefan