In smart environments interactive assistants can support the user's daily life by being ubiquitously available through any interaction device that is connected to the network. Focusing on graphical interaction, user interfaces are required to be flexible enough to be adapted to the actual context of the user. In this paper we describe an approach, which enables flexible user interface layout adaptations based on the current context of use (e.g. by changing the size of elements to visually highlight the important elements used in a specific situation). In a case study of the "4-star Cooking assistant" application we prove the capability of our system to dynamically adapt a graphical user interface to the current context of use.