"Display BUFFER by popping up a new window.
The new window is created on the selected frame, or in
`last-nonminibuffer-frame' if no windows can be created there.
-If sucessful, return the new window; otherwise return nil."
+If successful, return the new window; otherwise return nil."
(let ((frame (or (window--frame-usable-p (selected-frame))
(window--frame-usable-p (last-nonminibuffer-frame))))
window)