I tried a similar approach but I didn't finish it yet. The direct vector modification didn't work for me ... Probably because the indicator face is always reset after setting the indicator and I think the real screen update is made after the matrix generation. (If I understood right how the display engine works)

So with this approach the merge really creates a new face dynamically if needed.

Any way if that approach finally works for the general case I can fix also the other case. I will try it tomorrow because today I don't have time.

Thanks Alp specially for the Lisp code :-).

On May 4, 2019 5:59:37 PM GMT+02:00, Eli Zaretskii <eliz@gnu.org> wrote:
>> From: Alp Aker <alptekin.aker@gmail.com>
>> Date: Sat, 4 May 2019 11:44:11 -0400
>> Cc: Emacs devel <emacs-devel@gnu.org>
>> 
>> User customization could be accommodated by something like the below
>(naive) patch.  We define
>> fill-column-indicator face to have unspecified background; when
>displaying the indicator we merge the
>> indicator face into the current it->face_id (the same face used for
>the stretch glyph preceding the indicator).
>
>What about the case there's no stretch, i.e. the indicator directly
>follows the last character of the line?

-- 
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