In this paper, we introduce a new cooperative design and visualization environment, called "Integrare", which supports designers and developers in building dependable, component-based systems using a new behavior-oriented design method. This method has advantages in terms of its abilities to manage complexity, find defects and make checks of dependability. The environment integrates and unifies several tools that support multiple phases of the design process, allowing them to interact and exchange information, as well as providing efficient editing capabilities. It can help formalize individual natural language functional requirements as Behavior Trees. These trees can be composed to create an integrated tree-like view of all the formalized requirements. The environment manages complexity by allowing multiple users to work independently on requirements translation and tree editing in a collaborative mode. Once a design is constructed from the requirements, it can be visually simulated with respect to an underlying operational semantics, and formally verified by way of a model checker.