DTE

EnvDTE is an assembly-wrapped COM library containing the objects and members for Visual Studio core automation.

This namespace contains the IDTExtensibility2 interface. When implemented, its members allow you access to add-in events, such as when an add-in is started or shut down. When you create an add-in project, IDTExtensibility2 is implemented for you automatically. For information about responding to add-in events, see Components of an Add-In Project.