Re: Question about display engine

[Ergus]

On Sun, Sep 08, 2019 at 10:40:42AM +0200, martin rudalics wrote:
> > Please give a look to the attached patch and check if it is working fine
> > for you. (I added a new branch "extend_face_id" in savannah too)
>
> Thanks.  The problem with my standard use case on your branch is that
> when I customize 'font-lock-comment-face' to have a specific
> :background and :extend nil, the background I specified nevertheless
> extends to the end of the line.  So I wonder why it works to not
> extend the region while it apparently does not work to not extend
> 'font-lock-comment-face'.
>
> martin
I fixed that, try now please (it is in savannah already).

The problem was the merge I was doing in face_at_buffer_position which
was unconditionaly merged for props. I conditioned only the overlays.

It seems like font-lock-comment-face is a prop while region is an
overlay.

Right now as I modified merge_face_ref the conditional merge only works
when CONSP (face_ref) == false and I am not sure what to do to make it
work also for CONSP (face_ref) or if it even needed...