JDialog automatically hides when user clicks "show desktop" icon in task bar

Question

I have a Swing based Java application that needs to show a JDialog:

import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class JDialogHide {
  public void buildGUI() {
    final JFrame f = new JFrame("JFrame");
    // f.setResizable(false);
    JPanel p = new JPanel(new GridBagLayout());
    JButton btn = new JButton("SHow Dialog");
    p.add(btn,new GridBagConstraints());
    f.getContentPane().add(p);
    f.setSize(400,300);
    f.setLocationRelativeTo(null);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setVisible(true);
    btn.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent ae){
        JDialog jdialog = new JDialog(f, "JDialog");
        jdialog.setPreferredSize(new Dimension(300,200));
        jdialog.add(new JLabel("Test"));
        jdialog.setLocationRelativeTo(f);
        jdialog.pack();
        jdialog.setVisible(true);
      }
    });
  }
  public static void main(String[] args)
  {
    SwingUtilities.invokeLater(new Runnable(){
      public void run(){
        new JDialogHide().buildGUI();
      }
    });
  }
}

My problem is that the dialog automatically hides when the user clicks "Show Desktop" and again if they click the frame in task bar, the dialog doesn't show up.

i.e.,

Steps:

1. Open application and click "Show Dialog" button.
2. Now frame and dialog are visible. Then click the "Show Desktop" icon from task bar
3. Now if we select the application via task bar, the dialog doesn't show up.

I am using Ubuntu 14.04 LTS.

This solves my problem for jdialog but I cannot locate the dialog center:

JDialog jdialog = new JDialog((Window) null, "JDialog");

I can swap pack() and setLocationRelativeTo(), now the dialog is located at the center of the frame.

But the same problem occurs on JOptionPane.

import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class JDialogHide {
  public void buildGUI() {
    final JFrame f = new JFrame("JFrame");
    JPanel p = new JPanel(new GridBagLayout());
    JButton btn = new JButton("SHow Dialog");
    p.add(btn,new GridBagConstraints());
    f.getContentPane().add(p);
    f.setSize(400,300);
    f.setLocationRelativeTo(null);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setVisible(true);
    btn.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent ae){
          
        JDialog jdialog = new JDialog((Window) null, "JDialog");
        
        jdialog.setPreferredSize(new Dimension(300,200));
        JPanel p = new JPanel(new GridBagLayout());
        JButton btn = new JButton("Show showOptionDialog");
        p.add(btn,new GridBagConstraints());
        jdialog.getContentPane().add(p);
        
        btn.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent ae){
                JOptionPane.showOptionDialog(jdialog, "Test ?", "TEST ", JOptionPane.YES_NO_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE, null, null, null);
            }
        });
        
        jdialog.pack();
        jdialog.setLocationRelativeTo(null);
        jdialog.setVisible(true);
      }
    });
  }
  
  public static void main(String[] args)
  {
    SwingUtilities.invokeLater(new Runnable(){
      public void run(){
        new JDialogHide().buildGUI();
      }
    });
  }
}

How can I fix it for JOptionPane?