: When the user interface is specified, a picture is worth a thousand words, and the worst thing one can do is write a natural-language specification for it. Because this practice is still common, it is a challenging task to move from text-based requirements and problem-space concepts to a final UI design, and then back again. However, this activity is required frequently and is necessary to drive creative ideas. In our research we found that advanced UI specifications should therefore be made up of interconnected artefacts that have distinct levels action. With regards to the transparency and traceability of the rationale of the specification process, transitions and dependencies must be visual and traversable. For this purpose, we introduce a model-based user interface specification method and a corresponding experimental tool that interactively integrates interdisciplinary and informal models with different levels of fidelity of user-interface prototyping. With innovative styles of ...