I've installed Emacs 23 and have found that the compilation buffer (when using M-x compile) appears in a different position than it did in Emacs 22. The currently open buffer appears on the left and the compilation buffer on the right. How to I revert to the Emacs 22 behavior of having the current buffer open on the top and the compilation buffer on the bottom?
(Splitting the screen horizontally also is the case for the buffer list (M-x switch-to-buffer <tab>) buffer as well.)
It's probably the new split-window-preferred-function variable and split-window-sensibly function. Emacs now tries to figure out if it should split vertically or horizontally based on the window size (I assume you have a wide window). Try setting the split-width-threshold variable to nil.
This works for me in emacs 23 on linux :
(setq split-width-threshold most-positive-fixnum)
The following worked best for me:
;; Split windows in Emacs 22 compatible way
(setq split-height-threshold nil)
(setq split-width-threshold most-positive-fixnum)