Question

I have a few scripts that use the function pop-to-buffer a lot. It used to split the window horizontally, but now in Emacs 23 it splits the window vertically. I’ve dug through some of the elisp code but it’s not jumping out at me – how can I change this behavior of Emacs 23 to split horizontally again?

Answer 1

It’s listed in the NEWS for Emacs (C-h N):

*** display-buffer' tries to be smarter when splitting windows. The
new option
split-window-preferred-function’ lets
you specify your own function to pop
up new windows. Its default value
split-window-sensibly' can split a
window either vertically or
horizontally, whichever seems more
suitable in the current configuration.
You can tune the behavior of
split-window-sensibly by customizing
split-height-threshold’ and the new
option `split-width-threshold’. Both
options now take the value nil to
inhibit splitting in one direction.
Setting split-width-threshold to nil
inhibits horizontal splitting and gets
you the behavior of Emacs 22 in this
respect. In any case, display-buffer
may now split the largest window
vertically even when it is not as wide
as the containing frame.

I think what you want is:

(setq split-width-threshold nil)

(but I think you’re using the vertical versus horizontal splitting the opposite of what Emacs terminology is (which is counterintuitive to me as well))