In the last years, User Interface Description Languages (UIDLs) appeared as a suitable solution for developing interactive systems. In order to implement reliable and efficient applications, we propose to employ a formal description technique called ICO (Interactive Cooperative Object) that has been developed to cope with complex behaviours of interactive systems including event-based and multimodal interactions. So far, ICO is able to describe most of the parts of an interactive system, from functional core concerns to fine grain interaction techniques, but, even if it addresses parts of the rendering, it still not has means to describe the effective rendering of such interactive system. This paper presents a solution to overcome this gap using markup languages. A first technique is based on the Java technology called JavaFX and a second technique is based on the emergent UsiXML language for describing user interface components for multi-target platforms. The proposed approach offers a bridge between markup language based descriptions of the user interface components and a robust technique for describing behaviour using ICO modelling. Furthermore, this paper highlights how it is possible to take advantage from both behavioural and markup language description techniques to propose a new model-based approach for prototyping interactive systems. The proposed approach is fully illustrated by a case study using an interactive application embedded into interactive aircraft cockpits.