Exposing a Native Object Model Interface
If a UI element supports a native object model other than Microsoft Active Accessibility or UI Automation, it can expose the custom interface by responding to WM_GETOBJECT messages that include the OBJID_NATIVEOM object identifier. To respond, the UI element should return the value retrieved by a call to the LresultFromObject function.
A client can retrieve an interface from a UI element that supports a native object model by calling the AccessibleObjectFromWindow function and specifying OBJID_NATIVEOM as the second parameter.