Harlow takes a didactic approach to his subject, revealing its details one at a time with a careful explanation of each. He first explains how to build a plain, one-window application and then shows how to enhance it with the help of event handlers, additional GTK+ widgets, and some little-used interface elements. He presents complete examples to illustrate concepts, including a calculator and simple word processing application. Along the way, he does a great job of clearing up often confusing tasks, like creating menu bars and managing layouts.
Before wrapping up, Harlow explains the GDK, which you can use to create custom graphical elements. In a particularly grin-inducing section, he reveals how to write a version of the classic arcade game Defender with the help of the GDK. There's also a segment on creating your own widgets, so you can craft a customized yet consistent look for the programs you create. --David Wall