AddOn properties support the creation of custom objects, called AddOns, to add to a gadget. You can add rectangles, polygons, circles, arcs, lines, text, and images to any gadget to enhance its appearance. You can create any number of objects and arrange objects on top of or behind one another.
Figure 17-22 shows an example of adding two rectangles with rounded corners behind a meter gauge. To create this image, create one rectangle with a white border, then create another rectangle that is slightly larger. Use the same fill color for both rectangles. Place the larger rectangle behind the smaller rectangle.
Figure 17-23 shows the AddOns page. AddOns lists the two rectangles added to the meter gauge. The objects are listed in z order, which is the order from front to back.
Figure 17-24 shows the properties set for the larger rectangle. Notice that the size of the rectangle is not fixed. Rather, the size is a percentage of the gadget’s size. You define an AddOn’s size by specifying values for these four properties: Start X coordinate, Start Y coordinate, End X coordinate, and End Y coordinate. By using a relative size, AddOns adjust to the size of the gadget area.
Table 17-15 shows the properties for creating the different types of objects that you can add to a gadget.