ext.addChangeListener(plot);          
          
        //illustrates the usage of a shape item rendering strategy
        final CategoryCursor<String, String> cursor = new CategoryCursor<String,
                String>();
        r.setShapeIRS(new DefaultShapeIRS(r) {
            private static final long serialVersionUID = 1L;
            @Override
            public Shape getItemShape(int row, int column) {
                cursor.setPosition((String)dataset.getRowKey(row),