Many of the activities in this book require you to make use of existing files or sample programs. You'll find those files in the link given below.
Hands On AppGameKit Studio Volume 2: Files required by Activities
Supplement 1 (to Chapter 4): A Stopwatch GUI widget
Supplement 2 (to Chapter 4): A ColorPicker GUI widget
Supplement 3 (to Chapter 4): A TrafficLights GUI widget