other-window-or-frame

[Drew Adams]

If a frame is `one-window-p', command `other-window' silently does nothing.
It might be better to let it do `other-frame' in that case. The optional
second arg to `other-window' is not accessible interactively anyway, so what
about this:

1. Bind a new command to `C-x o', to replace `other-window'. It would do the
same thing except when `one-window-p' - in that case, it would do
`other-frame'.

2. Keep function `other-window' as is (with its second arg), for Lisp.

IOW (but with a better doc string):

 (defun other-window-or-frame (arg)
   "`other-frame', if `one-window-p'; otherwise, `other-window'."
   (interactive "p")
   (if (one-window-p) (other-frame arg) (other-window arg)))

 (define-key ctl-x-map "o" 'other-window-or-frame)