REQ: lookup-key to return raw binding

[David Reitter]

When I do something like

(lookup-key global-map [menu-bar file open-file])

all I get is the pure command, 'find-file-existing, in this case - but 
not the arguments :enable and :help that were defined in menu-bar.el:

(define-key menu-bar-file-menu [open-file]
  '(menu-item "Open File..." find-file-existing
              :enable (not (window-minibuffer-p
                            (frame-selected-window menu-updating-frame)))
              :help "Read an existing file into an Emacs buffer"))

However, I need the complete data in order to modify single elements of 
a menu-item for a given key.

Thanks.