bug#13073: 24.0.91; (window-width) doesn't take into account text-scale-adjust 'ed buffers

[Raimon Grau]

I'm trying to get the maximum number of chars that a line would accept
without overflowing of wrapping

(window-width) gives the number of columns of a given window, but if I
increase the size of the font, window-width doesn't change the
value returned.

steps to reproduce
$ emacs -Q
m-x (window-width) => 80
c-x c-+
m-x (window-width) => 80

visual-line-mode *does* take text scale adjustments into account, so the
knowledge about how to cope with text scale is in emacs somewhere at
least.

Regards,

Raimon Grau