title: WPF Change property of an object (that is a dependency property) in usercontrol
body: <p>I have a class</p>
  
  <pre><code>   class Export{
        TimeSpan SlowDownPosition{get; set;}
      }
  </code></pre>
  
  <p>Now this class is a dependency property of my usercontrol. And <code>SlowDownPosition</code> is bound to a TextBlock. I have a button that will reset the value to <code>zero</code>. But doing so doesn't update the UI, since <code>SlowDownPosition</code> is a property of a dependency property. </p>
  
  <pre><code>&lt;TextBlock Text="{Binding ElementName=TagMetaDataControl,Path=Export.SlowDownPosition}" /&gt;
  &lt;Button Content="X" Click="ResetAutoSlowPosition" /&gt;
  </code></pre>
  
  <p>On code behind</p>
  
  <pre><code>private void ResetAutoSlowPosition(object sender, RoutedEventArgs e)
      {
          Export.SlowDownPosition = TimeSpan.Zero;
      }
  </code></pre>
  
  <p>Is there a way to update the UI without making <code>SlowDownPosition</code> itself a dependency property?</p>