Today's applications become more and more complex, making it difficult to maintain the usability of the interface. User interfaces try to reduce the complexity and improve the usability of software, but it is not always possible to satisfy individual user needs. Therefore, users have to use support tools like help-manuals or require additional training. These support systems suffer from various problems, for example they do not adapt to the user's situation. Proactive User Interfaces (PUI) are intelligent content-driven interfaces that aim at guiding and teaching users according to their goals, preferences, needs and their current context. They provide cognitive support and assist users in every step of the human problem solving process, which consists of analyzing the current situation, choosing an option to change the situation (the next goal) and executing this option.
