title: WPF - DataTrigger animation doesn't work
body: <p>So I'm trying to make some animations during item removal from ItemsControl which is attached to <code>ObservableCollectio&lt;Item&gt;</code>
  I know I can't do this in unload event because it's simply too late to perform any animation so I've tried to do this using <code>DataTrigger</code></p>
  
  <p>My <code>xaml</code> file looks like this:</p>
  
  <pre><code> &lt;DataTemplate DataType="{x:Type MyApp:Item}"&gt;
          &lt;Border x:Name="ItemBorder"&gt;
              &lt;Label Content="{Binding Path=Name}" /&gt;
          &lt;/Border&gt;
          &lt;DataTemplate.Triggers&gt;
              &lt;DataTrigger Binding="{Binding Path=Removing}" Value="True"&gt;
                  &lt;DataTrigger.EnterActions&gt;
                      &lt;BeginStoryboard&gt;
                          &lt;Storyboard&gt;
                              &lt;DoubleAnimation Duration="0:0:1" From="1.0" To="0.0"
                                             Storyboard.TargetProperty="(Border.Opacity)" /&gt;
                          &lt;/Storyboard&gt;
                      &lt;/BeginStoryboard&gt;
                  &lt;/DataTrigger.EnterActions&gt;
              &lt;/DataTrigger&gt;
          &lt;/DataTemplate.Triggers&gt;
  &lt;/DataTemplate&gt;
  </code></pre>
  
  <p>and my <code>Item</code> class is simply:</p>
  
  <pre><code>public class Item : INotifyPropertyChanged
  {
      public event PropertyChangedEventHandler PropertyChanged = delegate { };
  
      private bool removing;
      public bool Removing {
          get
          {
              return removing;
          }
          set
          {
              removing = value;
              PropertyChanged(this, new PropertyChangedEventArgs("Removing"));
          }
      }
  
      // same with `Name` property
  }
  </code></pre>
  
  <p>I would like to start an animation by setting <code>item.Removing = true</code> but nothing happens.</p>
  
  <p>What am I doing wrong?</p>