The design of this part is very simple. It only needs one attribute, shape, that defines whether the part is round, rectangular, or triangular. To save work, the shape part will inherit from an existing VA Smalltalk part that already has most of the behavior this part needs. It will have a new Common Widget that does the actual drawing and keeps the part portable. Because the shape doesn't need to access any special operating system controls, it does not need a platform widget.