From Xojo Documentation
Displays the MenuItem as a contextual menu.
If no parameters are passed, the contextual menu appears at the location of the mouse pointer. If you pass the optional parameters, the contextual menu appears at the passed location. The coordinates are global, not just in the object that handles the MouseDown event.
The following example displays the Edit menu as a contextual menu. The code is in the MouseDown event handler of a RectControl. You can get the text of the selected item by accessing the Text property of the returned MenuItem.