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: Thu, 25 Feb 2016 11:46:58 -0500
> 
> > 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.
> 
> Exactly.  E.g. the behavior of vertical-motion could be "made to work" in
> the case where the motion is within the existing glyph matrices of the
> relevant windows, tho even in that case there could be several possible
> desirable behaviors depending on the intention behind the use of
> vertical-motion.

Basically, it can be made to work when the text around the boundary
uses the same font.

> > Which is why I strongly suggest to change Follow Mode so that it
> > forces all of its windows be of the same width.
> 
> And in that case my Elisp hook approach should be usable (assuming it's
> implementable ;-).

Could very well be, I didn't think seriously about such a situation
because Alan opposes to solve things like that.

> > With the current pixelwise control of window dimensions, this is easy.
> 
> Not sure about "easy" but yes.

I meant making the windows of equal width is easy.

> > However, Alan disagrees, and insists on supporting windows of unequal
> > width.
> 
> I think it might makes sense to allow the user to disable the "make all
> follow-mode windows same-width" and just live with the corresponding
> quirks, but I suspect that the amount of work needed to make follow-mode
> work "100% correctly" for the mixed-width case is really large (it will
> involve defining new primitives to replace vertical-motion, then
> changing all users accordingly).  What's the expected use-case that
> would justify such an effort?

I hope Alan has a good answer to that question.