JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JRootPane root = f.getRootPane(); // XXX Pay attention to these
Container content = root.getContentPane(); // XXX lines. They get more
content.add(new JButton("Hello")); // XXX explanation in the book.
f.pack();
f.setVisible(true);
