This functionality is supported only if you are using the Classic Agent.
Active X controls can be composed of objects which themselves expose properties and methods. An example is the Data control, which contains a Recordset control. Such contained objects are often referred to as dependent objects because they don’t exist outside the context of the containing control. In many cases, dependent objects are arranged into groups, or collections. For example, a TreeView control contains a collection of Node objects.
Users of the ActiveX control need a way to get at dependent objects. In the case of a simple dependent object, the outer control typically exposes a property that provides access to the contained object. In the case of a collection, the outer control provides access to the items in a collection through an intermediate object called a collection object.
You can get programmatic access to dependent objects by having the relevant control class inherit from a special class provided for this purpose: the CompoundControl class. This class provides methods for accessing the properties and methods of a simple dependent object, a collection object, or the individual items within a collection.