Architecture that integrates an unmanaged application as a hosted application into a design environment in a coherent yet usable manner such that the developer can use the hosted application's native functionality yet leverage rich productivity features provided by the IDE. The IDE includes a hosting component that comprises an application adaptor for providing an interface from the unmanaged application to the IDE. The IDE further includes a designer framework that provides user access to designer capabilities of the IDE. The host adaptor interfaces to the designer framework either directly and/or through an integration interface. Thus, the developer/user can then access the native functionality of the unmanaged application as well as the IDE functionality. This provides rich integration between the development environment and the hosted application, the end result of which is the designer interacting with the IDE.