Displays a popup menu.

Menu is shown at position pos, generated from a submenu specified by menuItemPath using a MenuCommand as menu context.

	// Shows the Assets menu when you right click on the contextRect Rectangle.
	class EditorUtilityDisplayPopupMenu extends EditorWindow {
		function OnGUI () {
			var evt = Event.current;
			var contextRect = Rect(10,10,100,100);
			if(evt.type == EventType.ContextClick) {
				var mousePos = evt.mousePosition;
				if (contextRect.Contains (mousePos)) {
					EditorUtility.DisplayPopupMenu (Rect (mousePos.x,mousePos.y,0,0), "Assets/", null);
					evt.Use();
				}
			}
		}
	}