+@defun frame-highest-window &optional frame position
+This function returns the topmost, leftmost window of frame @var{frame}
+at position @var{position}.
+
+If omitted, @var{frame} defaults to the currently selected frame.
+
+@var{position} is used to distinguish between multiple windows that abut
+the top of the frame: 0 means the leftmost window abutting the top of
+the frame, 1 the next-leftmost, etc. @var{position} can also be less
+than zero: -1 means the rightmost window abutting the top of the frame,
+-2 the next-rightmost, etc. If omitted, @var{position} defaults to 0,
+i.e. the leftmost highest window. If there is no window at the given
+@var{position}, @code{nil} is returned.
+@end defun
+
+The following three functions work similarly.
+
+@defun frame-lowest-window &optional frame position
+This function returns the lowest window on @var{frame} which is at
+@var{position}.
+@end defun
+
+@defun frame-leftmost-window &optional frame position
+This function returns the leftmost window on @var{frame} which is at
+@var{position}.
+@end defun
+
+@defun frame-rightmost-window &optional frame position
+This function returns the rightmost window on @var{frame} which is at
+@var{position}.