Methods and apparatus, including computer program products, for implementing a computer system that provides a model, a first view and at least a second view for presenting the model, a first controller and at least a second controller for manipulating the model. The first and second views relate to the first and second controllers, respectively. The computer system further comprises at least a first context, a second context and a third context. A user interface element of the first view binds to a first structure element of the first context and a user interface element of the second view binds to a second structure element of the second context. The first structure element and the second structure element reference a third structure element of the third context.