Why does GiftedMotion not look like the screenshot in the handbook, when I start it?

The screenshot of GiftedMotion in the handbook was taken using the Nimbus theme, which is suppose to become the default theme in Java, eventually replacing the old Ocean theme. Nimbus is shipped with Java 6 Update 10 and up, but not necessarily enabled by default. To enable it, you have to set the system property swing.defaultlaf to com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel.