Primitive visual parts are user interface components, such as windows, forms, push buttons, and scales. For most controls, three objects cooperate to make the part complete. These objects are the part itself, the common widget, and the platform widget. Most controls follow this three-layered approach, where each layer has a special role:

In this section, you will build a part that displays graphical shapes, like circles, rectangles, and triangles. Although the shape part doesn't really do anything, it is useful for making your user interfaces more attractive. This part is more complicated to build than the ones you have learned about so far, because it requires a new Common Widget class.

You will also learn new techniques for customizing your part's settings view, pop-up menu, and other Composition Editor characteristics.