Automated generation of Window / Icon / Menu / Pointing Device User Interfaces (WIMP UIs) has some potential, but there are still many unresolved issues involved, that lead, e.g., to usability problems. In particular, there are several problems concerning the derivation of behavior models of such user interfaces from a high-level interaction model. These problems are related to parallelism and granularity of communication units. In this paper, we present a new process for the automated derivation of a WIMP-UI behavior model from a given high-level Discourse Model. Our new process can handle parallelism in these models and supports different granularities of communication units. This solves certain problems of WIMP-UI generation related to behavior models.