Okay, I found a solution. Instead of creating the Display2D in the init() method, I moved it to the start() method and used this.controller.registerFrame() to register the frame with the controller. Now everything works, because I create the Display2D now after I have set the new grid dimensions in the controller window. It seems that I could move in principle everything from the init() method into the start() method. But why do I need then a separate init() ? Any comments ? Axel