popup-menu-normalize-position
popup-menu-normalize-position is a compiled Lisp function in `menu-bar.el
'.
(popup-menu-normalize-position POSITION)
Convert the POSITION to the form which `popup-menu' expects internally.
POSITION can an event, a posn- value, a value having
form ((XOFFSET YOFFSET) WINDOW), or nil.
If nil, the current mouse position is used.