bug#40856: Feature request: support arbitrary propertized strings in wrap-prefix specifications

[Eli Zaretskii]

> Cc: 40856@debbugs.gnu.org
> From: Clément Pit-Claudel <cpitclaudel@gmail.com>
> Date: Sun, 26 Apr 2020 13:23:15 -0400
> 
> What I meant to say is that if it's cheap enough to draw this:
> 
> ⟝ bbbbbbbbbbb
> ⟝ bbbbbbbbbbb
> ⟝ bbbbbbbbbbb
> ⟝ bbbbbbbbbbb
> ⟝ bbbbbbbbbbb
> 
> (where "⟝" is a wrap-prefix on all lines but the first)
> 
> … then it should be cheap enough to draw this:
> 
> ⟝ bbbbbbbbbbb
>    bbbbbbbbbbb
>    bbbbbbbbbbb
>    bbbbbbbbbbb
>    bbbbbbbbbbb
> 
> where the indentation is a specified space as wide as "⟝".

And what I meant is that the second one is more expensive, because for
each line but the first, Emacs will have to produce glyphs both for
"⟝" (to obtain its width) and for the stretch of space.