bug#17905: 24.3.50; writing with a giant font triggers RTL text entry

[Stefan Monnier]

> subtly break.  E.g., set scroll-margin to a non-zero value, then type
> "C-x C-+" enough time to enlarge the font significantly, and you will
> see that Emacs lets point enter the scroll margin (because it
> internally computes the scroll margin in pixels using the frame's
> default font).

I think this is OK: the scroll-margin's unit is "lines" but it is really
just a proxy for pixels.  Same as for window-margins.

> There was a similar problem in scroll commands, which caused
> inappropriate moving of point in the last line of the window; I fixed
> that as well.

Thanks Eli,


        Stefan