title: Modifying InnerXml of a text XmlNode
body: <p>I traverse an html document with SGML and XmlDocument. When I find an XmlNode which its type is Text, I need to change its value that has an xml element. I can't change InnerXml because it's readonly. I tried to change InnerText, but this time tag descriptor chars <code>&lt;</code> and <code>&gt;</code> encoded to <code>&amp;lt;</code> and <code>&amp;gt;</code>. for example:</p>
  
  <pre><code>&lt;p&gt;
      This is a text that will be highlighted.
      &lt;anothertag /&gt;
      &lt;......&gt;
  &lt;/p&gt;
  </code></pre>
  
  <p>I'm trying to change to:</p>
  
  <pre><code>&lt;p&gt;
      This is a text that will be &lt;span class="highlighted"&gt;highlighted&lt;/span&gt;.
      &lt;anothertag /&gt;
      &lt;......&gt;
  &lt;/p&gt;
  </code></pre>
  
  <p>What is the easiest way to modify the value of a text XmlNode?</p>