Support routines for popup menus

[Lennart Borgman (gmail)]

I just noticed that a library in Emacs opened a popup menu in such a way 
that the line it should give information about was hided. I think I have 
forgotten to send the two routines below which simplifies poping up 
menus alined to the point. Could they (or something similar) please be 
added to Emacs?

(defun point-to-coord (point)
  "Return coordinates of point in selected window.
The coordinates are in the form \(\(XOFFSET YOFFSET) WINDOW)."
  (let* ((pn (posn-at-point point))
         (x-y (posn-x-y pn))
         (x (car x-y))
         (y (cdr x-y))
         (pos (list (list x (+ y 20)) (selected-window))))
    pos))

(defun popup-menu-at-point (menu &optional prefix)
  "Popup the given menu at point.
This is similar to `popup-menu' and MENU and PREFIX has the same
meaning as there.  The position for the popup is however where
the window point is."
  (let ((where (point-to-coord (point))))
    (popup-menu menu where prefix)))