title: Change JFrame's background in Sea-Glass Look and Feel
body: <p>What's is the proper way to change to background of JFrame with Sea-Glass Look and Feel, so far I tried both :</p>
  
  <pre><code>frame.getContentPane().setBackground(Color.blue);
  </code></pre>
  
  <p>and</p>
  
  <pre><code>JPanel x = new JPanel();
  x.setBackground(Color.red);
  frame.setContentPane(x);
  </code></pre>
  
  <p>But it didn't make any effect :</p>
  
  <pre><code>import javax.swing.*;
  import com.seaglasslookandfeel.*;
  import java.awt.*;
  import java.awt.Color.*; 
  public class BORDER_TEST {
  public static void main(String[] a){
  
          EventQueue.invokeLater(new Runnable() {
              public void run() {
                  try {
  
                      UIManager.setLookAndFeel("com.seaglasslookandfeel.SeaGlassLookAndFeel");
                      JFrame frame = new JFrame();
                      JPanel x = new JPanel();
                      x.setBackground(Color.red);
                      frame.setContentPane(x);
  
                      //frame.getContentPane().setBackground(Color.blue);
                      frame.setPreferredSize(new Dimension(900,350));
                      frame.setAlwaysOnTop(true);
                      frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
                      frame.pack();
                      frame.setLocationRelativeTo(null);
                      frame.setVisible(true);
                      } catch (Exception e) {
                      e.printStackTrace();
                  }
              }
          });
      }    
  </code></pre>
  
  <p>}    </p>