The development of high quality user interfaces is not an easy task, usually involving
several people with different skills, knowledge and professional backgrounds. Various
prototypes on different levels of the system (backend, UI design, UI implementation) are
designed and considered for the development of the system, sometimes with support by
different tools. In this paper we propose an approach that consequently utilizes the
runtime view of the system being developed to provide an integrated development and
testing environment supporting all roles involved in the development process. Our
approach helps bridging the gap between the work of the designer, the usability expert,
and the developer by providing a common web-based system that allows all parties to
jointly work with the system under development during the creation of the user interface.