为什么我的命名WPF形状不受代码背后的影响？

Question

I have an Ellipse in my WPF application. I want to change the colour of its outline whenever it is double clicked. I found this (old) tutorial about making this work by using the available MouseDown event and checking for a ClickCount of two in the event handler. This is the simplest solution to my problem and I'd like to try and get this to work before creating an empty button Control Template .
However, I'm unable to find the clicked ellipse in my code behind file. Supposedly this works in the tutorial, but I'm wondering if I'm missing anything.
Here's the code that contains the ellipse. It is the 3rd column of a grid:

<ScrollViewer VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto" Grid.Column="3">
     <StackPanel Orientation="Vertical" Margin="3,1" Background="GhostWhite">
        <ItemsControl Name="FlowLinkItems" ItemsSource="{Binding FlowLinkList}">
           <ItemsControl.ItemTemplate>
              <DataTemplate>
                 <Grid Height="40">
                    <Ellipse Name="FlowLinkEllipse" Stroke="BlueViolet" Height="38" VerticalAlignment="Center" MouseDown="Ellipse_MouseDown"/>
                    <TextBlock TextAlignment="Center" HorizontalAlignment="Center" VerticalAlignment="Center" Text="{Binding Message}"></TextBlock>
                 </Grid>
              </DataTemplate>
           </ItemsControl.ItemTemplate>
        </ItemsControl>
     </StackPanel>
  </ScrollViewer>

In the tutorial, the code behind method worked like this:

private void Ellipse_MouseDown(object sender, MouseButtonEventArgs e)
  {
     if (e.ClickCount == 2)
     {
        FlowLinkEllipse.Stroke = "Red";
     }
  }

And the error I'm seeing is:

The name 'FlowLinkEllipse' does not exist in the current context

If this method is not possible I'm open to suggestions that are as simple as possible (I'm still new to WPF and the only thing my app will handle is this double click).
Note: I do have this line in my code behind and it works fine.
FlowLinkItems.MouseLeftButtonUp += FlowLinkItems_MouseLeftButtonUp;

Answer 1

As @Magus noted, you can't reference an item from code-behind, that is inside a DataTemplate . That should be no problem here, though: sender will contain a reference to the ellipse:

private void Ellipse_MouseDown(object sender, MouseButtonEventArgs e)
{
   if (ellipse as sender == null || e.ClickCount < 2)
      return;

   var ellipse = (Ellipse)sender;
   ellipse.Stroke = System.Windows.Media.Brushes.Red;
}