The need for computer supported collaboration has grown over the last years and made collaboration processes an important factor within organizations. This trend has resulted in the development of a variety of tools and technologies to support the various forms of collaboration. Many collaborative processes, e.g. strategy building, scenario analysis, root cause analysis and requirements engineering, require various collaboration support tools. Within these synchronous collaborative applications to create, evaluate, elaborate, discuss, and revise graphical models, e.g. data flow, fishbone and brainstorming diagrams, play an important role. Currently, the necessary tools are not integrated and flexible enough to support such processes. In this paper, we introduce a synchronous collaborative brainstorming diagram editor that is integrated in a flexible group support system. By this our approach goes beyond the current state of the art as we can be seamlessly integrated with other collaboration support tools such as textbased brainstorming, voting, etc.