bug#18601: 24.3.94; set-fringe-mode with left fringe 0 breaks window width calculations on Mac OS

[martin rudalics]

>> Did you really change that in between 24.3.93 and 24.3.94?
>
> Yes, in r117500.  That was one part of fixing display of truncated R2L
> lines in the many use cases you presented.

Meanwhile I came to that conclusion as well ;-)

> Btw, a simple way to avoid this side effect is to have a 1-pixel left
> fringe, i.e. "pay" 1 pixel.  That's not a high cost, IMO, if the
> motivation for removing the left fringe is to have 1 more column
> available for the same frame size.

This won't work on NS Emasc 24-4 which rounds pixel to column values.

martin