Re: Fill column indicator functionality

[Eli Zaretskii]

> Date: Fri, 15 Mar 2019 19:18:11 +0000 (UTC)
> From: Drew Adams <address@hidden>
> Cc: address@hidden, address@hidden, address@hidden
> 
> I understood that the simple fill-column indicator
> feature is not a more general feature, and it is not
> waiting for the fake-cursors feature.  My questions
> were about further possibilities and (perhaps) basing
> them on some common building blocks.

It is not about waiting, it's about the best design for each feature.

One of the features is similar to a cursor: it moves by user commands,
and can in principle be repositioned at every redisplay cycle.  The
other is entirely unlike a cursor: its position is more or less fixed,
and changes very rarely, if at all.  This fundamental difference leads
to 2 different designs and implementations, conflating which is IMO
not a good idea.  Cursor drawing is implemented in Emacs in a way that
is very different from normal glyph display, something that is
justified by its frequently-moving nature and the fact that there's
only one cursor per window.  The indicator discussed here is a very
different creature.