bug#16594: 24.3.50; very slow redraw when resizing windows horizontally

[Stefan Monnier]

> of the character size?  The idea was to make pixelwise effects
> obtainable only via setting `window-resize-pixelwise' to non-nil.

I see it now.  I just had assumed that window-resize-pixelwise was
already t by default (this assumption was based on the behavior while
dragging windows ;-).

I think the default for that should be t.  But we can delay this change
to post-24.4.


        Stefan