Extending a Primary Snap-in's View
Before building your own view extension, determine whether the Extended View extension provides the capability required by your application. For more information about the Extended View extension and how to determine if a custom view extension is necessary for your application, see Using the Extended View Extension.
A view extension must implement the IExtendView interface. Other than the methods inherited from the IUnknown interface, the IExtendView interface contains a single method, IExtendView::GetViews. The following C++ example code shows an implementation of IExtendView::GetViews.