Question about Sun's TextSamplerDemo in tutorial

I've stripped the code of the standard TextSampleDemo.java down to the
bare minimum to demonstrate the problem I'm trying to solve. I want a
button in the toolbar that will turn the selected text in the text pane
to bold when it is clicked. I've been beating my head against this
problem for a couple of days now with no luck.

Any help would be deeply appreciated.

--gary

Here's the code of the stripped down demo with the desired toolbar
button added:

import javax.swing.*;
import javax.swing.text.*;

import java.awt.*; //for layout managers and more
import java.awt.event.*; //for action events

public class TextSamplerDemo extends JPanel
                             implements ActionListener {
    private String newline = "\n";
    protected static final String textFieldString = "JTextField";

    public TextSamplerDemo() {

        setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS));
        JToolBar toolBar = buildToolbar();
        add(toolBar);

        //Create a text pane.
        JTextPane textPane = createTextPane();
        JScrollPane paneScrollPane = new JScrollPane(textPane);
        paneScrollPane.setVerticalScrollBarPolicy(
                        JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
        paneScrollPane.setPreferredSize(new Dimension(250, 155));
        paneScrollPane.setMinimumSize(new Dimension(10, 10));

        add(textPane);
    }

    public void actionPerformed(ActionEvent e) {
    }

    private JTextPane createTextPane() {
        String[] initString =
                { "This is an editable JTextPane, ",
//regular
                  "another ",
//italic
                  "styled ", //bold
                  "text ", //small
                  "component, " + newline,
  //large
                  "which supports embedded components..." +
newline,//regular
                  newline + "JTextPane is a subclass of JEditorPane
that " + newline +
                    "uses a StyledEditorKit and StyledDocument, and
provides " + newline +
                    "cover methods for interacting with those objects."
                 };

        String[] initStyles =
                { "regular", "italic", "bold", "small", "large",
                  "regular", "regular"
                };

        JTextPane textPane = new JTextPane();
        StyledDocument doc = textPane.getStyledDocument();
        addStylesToDocument(doc);

        try {
            for (int i=0; i < initString.length; i++) {
                doc.insertString(doc.getLength(), initString[i],
                                 doc.getStyle(initStyles[i]));
            }
        } catch (BadLocationException ble) {
            System.err.println("Couldn't insert initial text into text
pane.");
        }

        return textPane;
    }

    protected void addStylesToDocument(StyledDocument doc) {
        //Initialize some styles.
        Style def = StyleContext.getDefaultStyleContext().
                        getStyle(StyleContext.DEFAULT_STYLE);

        Style regular = doc.addStyle("regular", def);
        StyleConstants.setFontFamily(def, "SansSerif");

        Style s = doc.addStyle("italic", regular);
        StyleConstants.setItalic(s, true);

        s = doc.addStyle("bold", regular);
        StyleConstants.setBold(s, true);

        s = doc.addStyle("small", regular);
        StyleConstants.setFontSize(s, 10);

        s = doc.addStyle("large", regular);
        StyleConstants.setFontSize(s, 16);
    }

    private JToolBar buildToolbar() {

        JToolBar toolBar = new JToolBar();
        toolBar.setRollover( true );
        toolBar.setFloatable( false );
        JButton boldButton = new JButton("Bold");
        boldButton.setToolTipText( "Set selected text to bold" );
        boldButton.addActionListener( new ActionListener() {
            public void actionPerformed( ActionEvent e ) {
                // ?????????????????????
                // code here to make selected text bold
                // ?????????????????????
            }
        });
        toolBar.add( boldButton );
        return toolBar;
    }

    /**
     * Create the GUI and show it. For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI() {
        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);

        //Create and set up the window.
        JFrame frame = new JFrame("TextSamplerDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Create and set up the content pane.
        JComponent newContentPane = new TextSamplerDemo();
        newContentPane.setOpaque(true); //content panes must be opaque
        frame.setContentPane(newContentPane);

        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}