When the user interface should be specified, a picture is worth a thousand words, and the worst thing to do is write a natural language specification for it. Although 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. Especially for user interface specification, actors must frequently switch between high-level descriptions and low-level detailed screens. In our research we found out that advanced specifications should to be made up of interconnected artefacts that have distinct levels of abstraction. 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, a user interface specification method is introduced that interactively integrates interdisciplinary and informal modelling languages with different levels of fidelity of user interface prototyping. With an innovative experimental tool, we finally assemble models and design to an interactive user interface specifications.