bug#29279: Sharing the margins

[Eli Zaretskii]

> Cc: 29279@debbugs.gnu.org, joostkremers@fastmail.fm
> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Wed, 15 Nov 2017 00:39:34 +0200
> 
> On 11/14/17 5:30 PM, Eli Zaretskii wrote:
> 
> >> So I'd personally prefer to have all padding on one side.
> > 
> > But then requests for the rightmost (or leftmost) column will go
> > unsatisfied, for apparently no good reason.
> 
> It might be just a matter of interpretation: even if all the padding is 
> on the right, the "rightmost" column will remain such, among all the 
> visible columns.

Yes, but "being the rightmost" might mean "being right next to the
text", for whatever purposes.  A stretch of white space between the
text and the margin display might not be what the package wants.

> > It depends on your POV.  My POV is that it doesn't, since the window
> > dimensions and the dimensions of the text area are unaltered.  At
> > least one other person disagreed (vociferously).
> 
> But the effects are almost entirely the same, aren't they? Both the 
> change of margin width and the change of line numbers column width force 
> the reflowing of buffer contents display.

Again, as long as the text-area dimensions didn't change, it could be
argued that the hook shouldn't run.