bug#12380: other window related commands broken

[Doug Morgan]

emac version: 24.2.1
cygwin
Vista

Edit a file
C-x 2
(OK, now you have a two windows split horizontally)
C-x C-b
One of the windows **splits vertically**(!!) to show the buffer menu.  
Older versions of emacs (I don't know how far back you have to go) use 
the "other" window of the two horizontally split window to display the 
menu.  The old way is by far the better way.  The same thing happens 
with C-x 4 C-f and I think other C-x 4 commands. All make for annoying 
work cleaning up your windows after the unwanted vertical splits happen.

Doug