title: RichTextBox inside Expander in WPF
body: <pre><code>&lt;Expander Header="More options" Margin="281,218,39,12"&gt;
      &lt;Button Height="29" Width="111"&gt; hello &lt;/Button&gt;
  &lt;/Expander&gt;
  </code></pre>
  
  <p>The above code works. But:</p>
  
  <pre><code>&lt;Expander Header="More options" Margin="281,218,39,12"&gt;
      &lt;RichTextBox Name="richTextBox1" Margin="100,50,200,30" Height="30" Width="80"&gt;
          &lt;FlowDocument&gt;
              &lt;Paragraph&gt;Hi how are you?&lt;/Paragraph&gt;
          &lt;/FlowDocument&gt;
      &lt;/RichTextBox&gt;
  &lt;/Expander&gt;
  </code></pre>
  
  <p>This will not work. Why? How to make this work?</p>