最大高さ制限のある JDialog のサイズを動的に調整するにはどうすればよいですか?

<code class="java">import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;

public class ListDialog {

    // Initial number of items and maximum height
    private static final int INITIAL_COUNT = 5;
    private static final int MAX_HEIGHT = 200;

    private JDialog dlg = new JDialog();
    private DefaultListModel model = new DefaultListModel();
    private JList list = new JList(model);
    private JScrollPane sp = new JScrollPane(list);
    private int count = INITIAL_COUNT;

    public ListDialog() {
        JPanel panel = new JPanel();
        panel.add(new JButton(new AbstractAction("Add") {

            @Override
            public void actionPerformed(ActionEvent e) {
                append();
                sp.revalidate();
                dlg.pack();

                // Check if maximum height exceeded
                if (dlg.getHeight() > MAX_HEIGHT) {
                    list.setVisibleRowCount(count);
                }
            }
        }));

        // Create initial items
        for (int i = 0; i < INITIAL_COUNT; i++) {
            this.append();
        }

        list.setVisibleRowCount(INITIAL_COUNT);
        dlg.add(sp, BorderLayout.CENTER);
        dlg.add(panel, BorderLayout.SOUTH);
        dlg.pack();
        dlg.setLocationRelativeTo(null);
        dlg.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
        dlg.setVisible(true);
    }

    private void append() {
        model.addElement("String " + String.valueOf(++count));
        list.ensureIndexIsVisible(count - 1);
    }

    public static void main(String[] a_args) {
        new ListDialog();
    }
}</code>