• the method getSize() to get the dimensions of the traffic light canvas that was assigned by the layout manager.

• the Dimension class

• the methods getColor() and setColor()

• the methods drawOval() and fillOval()

• the methods getMinimumSize() and getPreferredSize that are used by some of the layout managers to help determine the size of components

In the class ChangeableTL, note the use of

• Static named constants

• Event handlers in two different classes. Which goes where and why?

• Use of the public Event instance variables e.target, e.x, and e.y

• Casting an Object, e.target, to a ChangeableTL. Why is this necessary? Why doesn't polymorphism take care of this?