problem with insertComponent

From: Daniel Forster (trx_at_zhwin.ch)
Date: 06/24/04 

Date: Thu, 24 Jun 2004 16:57:07 +0100

does someone know, why this simple program does not work???
each time it detects ".*", this should be replaced by a button.

insertcomponent doesn't work. i tried with invokeLater and invokeAndWait -
nothing worked.

import java.awt.*;
import javax.swing.text.*;
import javax.swing.event.*;
import javax.swing.text.rtf.*;
import javax.swing.*;

class DF extends DocumentFilter {
  JTextPane tp;
  static boolean exit=false;
  public DF(JTextPane t) {
    tp=t;
  }
  public void replace(DocumentFilter.FilterBypass fb,int offset,int
length,String text,AttributeSet attr) throws BadLocationException {
    if (exit) return;
    fb.replace(offset,length,text,attr);
    String pt=fb.getDocument().getText(0,fb.getDocument().getLength());
    for (int x=1;x<pt.length();x++)
      if ((pt.charAt(x)=='*')&&(pt.charAt(x-1)=='.')) {
        exit=true;
        tp.select(x-1,x+1);
        tp.insertComponent(new JButton("Click Me"));
        exit=false;
      }
  }
}

public class Uni extends JFrame {
  protected JTextPane m_monitor;
  DefaultStyledDocument m_doc;
  public Uni() {
    m_monitor=new JTextPane();
    RTFEditorKit m_kit=new RTFEditorKit();
    m_monitor.setEditorKit(m_kit);
    StyleContext m_context=new StyleContext();
    m_doc=new DefaultStyledDocument(m_context);
    m_monitor.setDocument(m_doc);
    getContentPane().add(m_monitor,BorderLayout.CENTER);
    ((AbstractDocument)m_monitor.getDocument()).setDocumentFilter(new
DF(m_monitor));
    m_monitor.replaceSelection(" .* - * - .* * * ");
    setSize(600,400);
    setVisible(true);
  }

  public static void main(String[] args) {
    Uni u=new Uni();
  }
}