<oMenuItem>:isPopUp() --> lPopUpStatus

        Returns a logical value that indicates whether the menu item's data
        property contains a pop-up menu.  A value of true (.T.) indicates
        that MenuItem:data contains a PopUpMenu object; otherwise, a value of
        false (.F.) indicates that it does not.

        isPopUp() is a method of the MenuItem class that is used for
        determining whether a menu item is a branch in a menu tree.  When a
        menu item is selected, typically one of two results will occur.  If
        it is a menu tree branch, its pop-up menu is opened; otherwise, its
        code block will be evaluated.