Diagrams (e.g., trees for hierarchical structures, or graphs for finite state machines) are often needed as part of advanced user interfaces, and are frequently specific to a user's application. The implementation of editors for diagrams should be supported by a tool and based on a formal model. This paper gives an overview of DiaGen, our generator for diagram editors. An editor for a certain kind of diagrams is generated from a specification, which includes a hypergraph grammar to describe...