JTabbedPane cause second paint

Question

I have a problem with JTabbedPane that has me stumped. When a TabbedPane is displayed, it causes it's parent component to repaint itself. This appears to happen because the TabbedPane wants to paint the contents of it's visible tab. If I don't add any tabs to the TabbedPane, the problem goes away. I have given a simple example to demonstrate.import java.awt.*;
import javax.swing.*;
class TabTest
  public static void main(String[] args)
    JFrame frame = new JFrame("TabTest");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JTabbedPane tabbedPane = new JTabbedPane();
    tabbedPane.addTab("First Tab", new JPanel());
    tabbedPane.addTab("Second Tab", new JPanel());
    JPanel contentPane = new JPanel(new BorderLayout()){
      protected void paintComponent(Graphics g)
        try
          // sleep so we can watch the painting issue occur
          System.out.println("contentPane.paintComponent()");
          Thread.currentThread().sleep(1000);
        catch(Exception e){}
        super.paintComponent(g);
    contentPane.add(tabbedPane, BorderLayout.CENTER);
    frame.setContentPane(contentPane);
    frame.setBounds(300,300,300,300);
    frame.setVisible(true);
}My only solution so far is to use a CardLayout and simulate a TabbedPane like interface. When the tabs have some components on them, you can see a flicker, which is my main problem with this.

Answer 1

v1.4.2
Yes that is what I mean. Only a TabbedPane requires a second paint of the frame. When the tabbedPane has some components on it, requiring more painting, you will notice a flicker when displaying the window. The flicker is gone if your remove all tabs from the tabbedPane. If you get rid of the tabbedPane and put a regular JPanel there, only one paint is performed. Or if you put a JPanel with a cardlayout only one paint is performed.
In my application, it is actaully a modal JDialog with a borderlayout and the tabbedPane is put in the WEST region. If I do the little sleep(), I can see the borderlayouts CENTER, BOTTOM and NORTH regions painted and then the screen is wipped and finally get the WEST region...the tabbedPane. This requires a second paintComponent() call and several invalidates. This causes an annoying flicker which is only removed by removing all tabs from the tabbedPane or by using a CardLayout instead.