title: Wpf Replace Text into RichTextBox
body: <p>I work in WPF C#, i want to replace text into RichtextBox
  i load my rtf File who contain picture it's work fine.</p>
  
  <p>If i use this :</p>
  
  <pre><code>    ReposLettresFusion m_ReposLettresFusion = new ReposLettresFusion();
      TextRange range = new TextRange(rtb.Document.ContentStart, rtb.Document.ContentEnd); 
      FileStream fStream = new FileStream(@pPath, FileMode.Create);
  
      range.Text = m_ReposLettresFusion.Fusion(pPkGuidLettre, range.Text);
      range.Save(fStream, DataFormats.Rtf);
      fStream.Close();
  
      rtb.LoadRtf(pPath);
      m_ReposLettresFusion = null;
      range = null;
  </code></pre>
  
  <p>It's change my text but i loose my picture and fonts all my formatting.</p>
  
  <p>How i can replace text and keep all formatting of the Rtf</p>
  
  <p>Thank you</p>