Java StyledEditorKit create rich text editor

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Insets;

import javax.swing.ButtonGroup;
import javax.swing.JCheckBoxMenuItem;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JPanel;
import javax.swing.JRadioButtonMenuItem;
import javax.swing.JTextPane;
import javax.swing.text.StyledEditorKit;

public class Main {

  public static void main(String[] args) {
    JPanel main = new JPanel();
    main.setLayout(new BorderLayout(3, 3));
    main.setPreferredSize(new Dimension(433, 312));
    JTextPane textPane = null;/* w  w  w  .  j a v a 2  s  .  com*/

    textPane = new JTextPane();
    textPane.setCaretPosition(0);
    textPane.setMargin(new Insets(5, 5, 5, 5));

    main.add(textPane, BorderLayout.CENTER);

    JMenuBar menuBar = new JMenuBar();

    JMenu fontsMenu = new JMenu("Fonts");

    ButtonGroup fontGroup = new ButtonGroup();
    JRadioButtonMenuItem serifItem = new JRadioButtonMenuItem("Serif");
    serifItem.setAction(new StyledEditorKit.FontFamilyAction(Font.SERIF, Font.SERIF));
    fontsMenu.add(serifItem);
    fontGroup.add(serifItem);

    JRadioButtonMenuItem sansSerifItem = new JRadioButtonMenuItem("SansSerif", null);
    sansSerifItem.setSelected(true);
    sansSerifItem.setAction(new StyledEditorKit.FontFamilyAction(Font.SANS_SERIF, Font.SANS_SERIF));
    fontsMenu.add(sansSerifItem);
    fontGroup.add(sansSerifItem);

    JRadioButtonMenuItem monoItem = new JRadioButtonMenuItem("MONO SPACED", null);
    monoItem.setAction(new StyledEditorKit.FontFamilyAction(Font.MONOSPACED, Font.MONOSPACED));
    fontsMenu.add(monoItem);
    fontGroup.add(monoItem);

    menuBar.add(fontsMenu);

    JMenu sizeMenu = new JMenu("Size");

    ButtonGroup sizeGroup = new ButtonGroup();
    JRadioButtonMenuItem size12Item = new JRadioButtonMenuItem("12");
    size12Item.setSelected(true);
    size12Item.setAction(new StyledEditorKit.FontSizeAction("12", 12));
    sizeMenu.add(size12Item);
    sizeGroup.add(size12Item);

    JRadioButtonMenuItem size14Item = new JRadioButtonMenuItem("14");
    size14Item.setAction(new StyledEditorKit.FontSizeAction("14", 14));
    sizeMenu.add(size14Item);
    sizeGroup.add(size14Item);

    JRadioButtonMenuItem size16Item = new JRadioButtonMenuItem("16");
    size16Item.setAction(new StyledEditorKit.FontSizeAction("16", 16));
    sizeMenu.add(size16Item);
    sizeGroup.add(size16Item);

    JRadioButtonMenuItem size18Item = new JRadioButtonMenuItem("18");
    size18Item.setAction(new StyledEditorKit.FontSizeAction("18", 18));
    sizeMenu.add(size18Item);
    sizeGroup.add(size18Item);

    menuBar.add(sizeMenu);

    JMenu styleMenu = new JMenu("Style");

    JCheckBoxMenuItem boldItem = new JCheckBoxMenuItem("Bold", null);
    styleMenu.add(boldItem);
    boldItem.setAction(new StyledEditorKit.BoldAction());

    JCheckBoxMenuItem italicItem = new JCheckBoxMenuItem("Italic", null);
    italicItem.setAction(new StyledEditorKit.ItalicAction());
    styleMenu.add(italicItem);

    menuBar.add(styleMenu);

    JFrame frame = new JFrame("java2s.com");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    frame.add(main);

    frame.setJMenuBar(menuBar);
    frame.setSize(300, 250);
    frame.setVisible(true);
  }
}