bug#59141: 28.1.90; Face :extend when all the line but trailing \n is invisible

[Eli Zaretskii]

> From: Abdul-Lateef Haji-Ali <abdo.haji.ali@gmail.com>
> Cc: yantar92@posteo.net, 59141@debbugs.gnu.org, kevin.legouguec@gmail.com,
>  juri@linkov.net
> Date: Fri, 11 Nov 2022 19:47:45 +0000
> 
> 
> On 11/11/2022, Eli Zaretskii wrote:
> > I don't think I understand the question.  What do you mean by "overlay
> > rendering"?  An overlay can produce text only if it has a
> > before-string or after-string property, so what do you mean by
> > "arbitrary text"?
> 
> I might be using the wrong terms here, but I think the idea is 
> straightforward.
> According to `buffer-invisibility-spec` docs
> 
> ,----
> | If the (ATOM . ELLIPSIS) form is used, and ELLIPSIS is non-nil, an
> | ellipsis will be displayed after the invisible characters.
> `----
> 
> so I am wondering if a new form like `(ATOM . STRING)` can be supported so 
> that STRING can be displayed after the invisible characters instead of 
> ellipses.

This is what the 'display' property already does, so I don't see why
we'd need yet another way of replacing some buffer text with a
different text on display.

> The suggested solution is have an outline entry include the new line 
> character (so that the whole extended lines is hidden). The displayed text 
> after the invisible text would then be "...\n".

AFAIU, your proposal will make this:

,----
| * A
| TextA
| * B
| TextB
`----

be displayed like this after hiding the bodies:

,----
| * A* B
`----

because the newline will be hidden

AFAIU, this is not what Org wants to display when the bodies of the
headings are hidden.