Abstract user interface prototypes offer designers a form of representation for specification and exploration of visual and interaction design ideas that is intermediate between abstract task models and realistic or representational prototypes. Canonical Abstract Prototypes are an extension to usage-centered design that provides a formal vocabulary for expressing visual and interaction designs without concern for details of appearance and behavior. A standardized abstract design vocabulary facilitates comparison of designs, eases recognition and simplifies description of common design patterns, and lays the foundations for better software tools. This paper covers recent refinements in the modeling notation and the set of Canonical Abstract Components. New applications of abstract prototypes to design patterns are discussed, and variations in software tools support are outlined.