bug#16647: Imprecisions with window-resizing cursors

[martin rudalics]

> First impressions: Before splitting the window horizontally (with the
> backwardsly-named split-window-vertically), I notice that I get the
> changed mouse cursor indicating that I can resize the window whenever I
> cross the mode line / bottom divider, but, in fact, I am only able to
> use it (to increase the size of the minibuffer) when the minibuffer is
> active. When the minibuffer is inactive, I can't resize it, yet the
> mouse cursor still changes indicating that I can. Presumably this is a
> bug.

I know.  I'll look into this eventually.

> But:
>
>     emacs -Q
>     M-: (set-frame-parameter nil 'bottom-divider-width 10) RET
>     M-: (setq mouse-autoselect-window t)
>     Drag the window divider up a few pixels (but less than one line)
>
> Moving the mouse cursor upwards is as before.
>
> Moving the mouse cursor downwards is as before except that when it
> crosses the bottom of the bottom divider into the bottom window, the
> focus changes to the bottom window, _but_ the resizing mouse cursor
> continues to be displayed well in to the bottom window, but will not
> resize the window if clicked on there -- indeed clicking on it, I can
> select text in the bottom window while it is still displayed as a
> resizing cursor!
>
> At 19:29 -0400 on Sunday 2014-02-23, E. Sabof wrote:
>
>> To me it looks like some code expects a full "character" movement, before it 
registers a change in location.
>
> I get a similar impression. Noticing that split-window-below is
> documented to take only an argument that is an integral number of lines
> (it does something when passed a decimal fraction but I can't figure out
> what it is -- I thought it might then treat the argument as pixels but
> that's not it), I wondered if the code assumes that the split can only
> be an integral number of lines below the top of the window above, or
> something, and fails to take into account a fractional position?

Try with `frame-resize-pixelwise' non-nil in your .emacs.  Maybe it's
the size hints.

martin