bug#29279: Sharing the margins

[Dmitry Gutov <dgutov@yandex.ru>]

On 11/15/17 5:42 AM, Eli Zaretskii wrote:

>> 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.

So far, I doubt it's going to come up as a real, hard requirement. But 
we'll probably see.

> A stretch of white space between the
> text and the margin display might not be what the package wants.

OK, can we think of a case where a package might want its margin content 
to be _as far away_ from the text as possible? And become troubled if 
some padding stands between it and the window edge?

If not, let's put all padding on the outside and be done with that concern.

>> 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.

That's some creative nomenclature lawyering. :-)

OK then, what's the practical problem with saying that margins are also 
part of "text-area dimensions"?