private synchronized void closeAll() {
    try {
      // Close all child window
      WindowManager.closeAll();

      // Remove all child component
      pnlThread.setVisible(false);
      pnlUser.setVisible(false);
      pnlThread.removeAll();
      clearAll(txtBoard);
      tblUser.setData(new Vector());
      Thread.sleep(500);
    } catch (Exception e) {
      e.printStackTrace();
      MessageBox.showMessageDialog(this, e, Global.APP_NAME, MessageBox.ERROR_MESSAGE);
    }
  }