Dynamic design-time extensions support in an integrated development environment

An Integrated Development Environment (IDE) is provided which comprises a visual designer that supports at least two avenues of extension. First, the visual designer may be extended with entirely new features by adding a visual designer extension. The visual designer extension is a deriving class of an extension server object. The extension server object may be provided along with the IDE. The visual designer extension manages a list of extension objects, and exposes a service provider to such extension objects. The visual designer extension can request and publish services through the service provider. Second, the visual designer may be extended with new variations of existing features by adding additional extension objects that derive from, and are managed by, an existing visual designer extension. These two modes of extension are supported by a novel visual designer framework described herein.