title: How to avoid flickering when using an asynchronous binding
body: <p>I've created an example to illustrate my problem.</p>
  
  <p>ViewModel:</p>
  
  <pre><code>public class VM : INotifyPropertyChanged
  {
      private double _value = 1;
      public double Value
      {
          get { return _value; }
          set
          {
              _value = value; 
              OnPropertyChanged();
          }
      }
  
      public VM()
      {
          var timer = new DispatcherTimer();
          timer.Interval = TimeSpan.FromTicks(1);
          timer.Tick += (s, e) =&gt; { Value += 1; };
          timer.Start();
      }
  
      // OnPropertyChanged stuff ... 
      }
  }
  </code></pre>
  
  <p>View:</p>
  
  <pre><code>&lt;Window.DataContext&gt;
      &lt;namespace:VM/&gt;
  &lt;/Window.DataContext&gt;
  &lt;Grid&gt;
      &lt;TextBox Text="{Binding Value, IsAsync=True, FallbackValue=Test}"/&gt;
  &lt;/Grid&gt;
  </code></pre>
  
  <p>When running my application the text in the textbox flickers. During the update process the FallbackValue is displayed, which makes no sense to me.</p>
  
  <p>Does anyone knows the purposes or what are the benefits that during the update process the FallbackValue is displayed? Is there a way to display the old Value during an async update process?</p>