Mobile devices available today are very heterogeneous with regard to their display and input capabilities and used software platform configurations. This leads to a complex development process for applications which have to target a wide range of devices. Adapting the interface of an application to the current context of the user adds another burden to developers, while improving the user experience. Therefore we developed an XUL-based User Interface Framework which eases the development of mobile applications by separating the UI adaption from the application logic and offering portability to different Java ME platform configurations. Using this framework the user interface (UI) adapts itself automatically on context-changes and changes to different screen resolutions or orientations without increasing code complexity for the developers.