PopupStart is the class for context-sensitive menus that pop up when you click the right-mouse button or some other key combination. Popup menu items change dynamically, depending on the point at which the popup menu appears.
To use popup menus, you define a new class, which inherits from the PopupMenu class. The children of this class should be the menu items on the popup menu. You then include the popup menu class as a child of each control to which the popup menu applies. For information on defining your own classes, see the winclass declaration.