bug#3142: 23.0.92; split-window-prefered-function should be able to use split-window-horizontally/split-window-vertically

[Juri Linkov]

> + (defcustom split-window-preferred-function 'split-selected-window
> +   "Function called by `display-buffer' to split a window.
> + The window that shall be split is selected when this function is
> + called.  The function is supposed to either return the new window
> + or nil if the window can (or shall) not be split."
> +   :type 'function
> +   :version "23.1"
> +   :group 'windows)

If setting this option to `split-window-horizontally' and
`split-window-vertically' is possible and it works correctly
with these value, then I suggest adding them as constants,
e.g. "Always split horizontally" and "Always split vertically".

Also I suggest keeping the common function name prefix "split-window-",
i.e. instead of `split-selected-window' to name it something like
"split-window-sensibly" or "split-window-with-thresholds".

-- 
Juri Linkov
http://www.jurta.org/emacs/