While model based design of platform independent application logic has already shown significant success, the design of platform independent user interfaces still needs further investigation. Nowadays, user interface design is usually platform specific or based on C-level cross-platform libraries. In this paper, we propose a MDA like design approach for user interfaces based on the transformation of UML t different levels of abstraction. This enables platform independent design of user interfaces and a clear separation of UI and application logic design while enabling full use of native controls in the actual user interface implementation.