Re: The future of Follow Mode - a proposal.

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: emacs-devel@gnu.org
> Date: Wed, 24 Feb 2016 19:30:55 -0500
> 
> I live in a world where wrapped lines are sufficiently rare that I don't
> really care and rarely think about what can happen in those cases.
> 
> But now that I think about it: I'm not sure how vertical-motion could
> handle a "multiple-window" case where the windows don't have the same
> width (same thing in other similar cases, such as with overlays with
> a `window' property that make them only apply to some of the multiple
> windows, or when the windows aren't all in the same frame and don't use
> the same font).  The desired semantic seems undefined except for the
> case where the vertical motion is applied to the "currently displayed
> state" (so we know when to use which window data).

Actually, vertical-motion completely breaks in that case.  I don't
even see a way that will allow to solve that situation in principle,
except in some very specific and restricted use cases.  Which is why I
strongly suggest to change Follow Mode so that it forces all of its
windows be of the same width.  With the current pixelwise control of
window dimensions, this is easy.  I think this will magically remove
many of the problems that currently plague Follow Mode, and leave us
with something we can reasonably easy to solve and maintain.

However, Alan disagrees, and insists on supporting windows of unequal
width.