The following code should make it so that the background color will turn to blue when a button is clicked, it doesn't work when the app is launched via web start.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.plaf.ColorUIResource;


public class UIManagerTester {
    public static void main( String[] args ) {
        try {
            UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());
        } catch(Exception e) {
            e.printStackTrace();
        }
        new JButton();
        UIManager.put("Label.foreground", new ColorUIResource(Color.red));
        UIManager.put("Button.select", new ColorUIResource(Color.blue));
        UIManager.put("Button.foreground", new ColorUIResource(Color.red));
        UIManager.put("Button.background", new ColorUIResource(Color.black));


        JFrame frame = new JFrame( "Test" );

        JPanel aPanel = (JPanel) frame.getContentPane();
        aPanel.setLayout(new FlowLayout());
        aPanel.add(new JLabel("This is test label"));
        JButton button = new JButton("Test Button");
        button.setContentAreaFilled(true);
        aPanel.add(button);

        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });

        frame.pack();
        frame.show();
    }
}