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

[Abdul-Lateef Haji-Ali]

On 11/11/2022, Eli Zaretskii wrote:
>> 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.

Yes indeed, but I assumed that controlling visibility in the buffer by 
modifying the visibility-spec would be desirable, which is difficult to achieve 
with `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".
> ,----
> | * A* B
> `----
>
> because the newline will be hidden

At the moment, if the new line is included in the entry then the output would be
,----
| * A...* B
`----

However, if the displayed text after the invisible text is changed to "...\n" 
instead of "..." (through `display` or better yet through a change to 
invisibility-specs as I suggested) then the output is correct.