Many model-based approaches for user interface design start from a task model, for which the ConcurTaskTrees notation is frequently used. Despite this popularity and the importance that has been given to a close relation with UML, no relation has been established with UML state machines, which have been shown to be useful for the description of the behavior of user interfaces. This paper proposes a semantic mapping of tasks and all temporal relations of the ConcurTaskTrees to UML state machines which forms the basis for a compact dialog modeling notation using UML state machines. The proposed approach uses a UML profile to reduce the visual complexity of the state machine.