title: Format TimeSpan value in xaml
body: <p>I have code :</p>
  
  <pre><code>&lt;Label Width="100"&gt;
      &lt;Label.Content&gt;
          &lt;PriorityBinding&gt;
              &lt;Binding Path="CurrentTime" StringFormat="Total: HH:MM:SS"  IsAsync="True"/&gt;
          &lt;/PriorityBinding&gt;
      &lt;/Label.Content&gt;
  &lt;/Label&gt;
  </code></pre>
  
  <p>But it formats the timespan to <code>12:14:34.3456577</code>.
  How should I format the string to not show this part after the dot ?</p>