Bad window size calculation after using pack()

FULL PRODUCT VERSION :
openjdk version "1.6.0-internal"
OpenJDK Runtime Environment (build 1.6.0-internal-langel_02_jun_2008_10_58-b00)
OpenJDK Server VM (build 10.0-b19, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Linux towel.yyz.redhat.com 2.6.25-14.fc9.i686 #1 SMP Thu May 1 06:28:41 EDT 2008 i686 i686 i386 GNU/Linux

A DESCRIPTION OF THE PROBLEM :

The pack() method of the Window class allow to resize the window based on the
contents preferred sizes, when using OpenJDK on the following example, the
window always have a empty area below (that does not happens of the Sun Java
binaries)

import java.awt.FlowLayout;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.WindowConstants;

public class TestFrame {
    public static void main(String[] args) {
        JFrame frame = new JFrame();
        JPanel panel = new JPanel(new FlowLayout());
        panel.add(new JButton("Testing..."));
        frame.setContentPane(panel);
        
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
    }
}



STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
run the test case

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Window should be framed around the center button
ACTUAL -
Window is longer than it should be. size calculated wrong

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.awt.FlowLayout;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.WindowConstants;

public class TestFrame {
    public static void main(String[] args) {
        JFrame frame = new JFrame();
        JPanel panel = new JPanel(new FlowLayout());
        panel.add(new JButton("Testing..."));
        frame.setContentPane(panel);
        
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
    }
}
---------- END SOURCE ----------