title: How to Add text in current RichTextBox text WPF
body: <p>I Want to add some text to my richtextbox.</p>
  
  <p><strong>Example</strong> Consider I have one Richtextbox and its text is "Uzair" and now I want to add "Ali".<br>
     <code>string myText = "Ali"<br>
      RichTextBox.Text += myText</code>  </p>
  
  <p>I don't know why there isn't a Text property of RichTextBox in WPF<br>
  Is there any alternative to <code>RichTextBox.Text</code> property?</p>