How do I retrieve text from a textblock inside a listbox and display the text in a textbox?

Question

How do I retrieve text from a textblock inside a listbox and display the text in a textbox?

What I want to do

First I want to be able to copy the text from the textblock inside the listbox

Then I want to display the text in the textbox

I tried using a visual tree helper but apparently it cannot find the 'FindName' method. Is there a better way to achieve this?

XAML Code

 <ListBox Name="ChatDialogBox" Height="550" ItemsSource="{Binding Path=Instance.Messages,Source={StaticResource Binder}}" > 
            <ListBox.ItemTemplate>  
                <DataTemplate>                   
                            <Grid>                       
                                <TextBlock Name="ChatMessage" Text="{Binding Text}" TextWrapping="Wrap" Width="430">         
                     <toolkit:ContextMenuService.ContextMenu>
                        <toolkit:ContextMenu Name="ContextMenu" >
                              <toolkit:MenuItem Name="Copy"  Header="Copy" Click="Copy_Click" />
                        </toolkit:ContextMenu>
                    </toolkit:ContextMenuService.ContextMenu>          
                                </TextBlock>                             
                            </Grid>                 
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

Code Behind

 private void Copy_Click(object sender, RoutedEventArgs e)
    {

        ContentPresenter myContentPresenter = FindVisualChild<ContentPresenter>(ChatDialogBox);
        DataTemplate myDataTemplate = myContentPresenter.ContentTemplate;
        TextBlock target = (TextBlock)myDataTemplate.FindName("ChatMessage", myContentPresenter);

    }


    private childItem FindVisualChild<childItem>(DependencyObject obj) where childItem : DependencyObject
    {
        for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
        {
            DependencyObject child = VisualTreeHelper.GetChild(obj, i);
            if (child != null && child is childItem)
                return (childItem)child;
            else
            {
                childItem childOfChild = FindVisualChild<childItem>(child);
                if (childOfChild != null)
                    return childOfChild;
            }
        }
        return null;
    }

Binder Class

 public class Binder : INotifyPropertyChanged
{
    static Binder instance = null;
    static readonly object padlock = new object();

    public Binder()
    {
        Messages = new ObservableCollection<Message>();
    }

    public static Binder Instance
    {
        get
        {
            lock (padlock)
            {
                if (instance == null)
                {
                    instance = new Binder();
                }
                return instance;
            }
        }
    }

    private ObservableCollection<Message> messages;
    public ObservableCollection<Message> Messages
    {
        get
        {
            return messages;
        }
        set
        {
            if (messages != value)
            {
                messages = value;
                NotifyPropertyChanged("Messages");
            }
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    private void NotifyPropertyChanged(String info)
    {
        if (PropertyChanged != null)
        {
            Deployment.Current.Dispatcher.BeginInvoke(() => { PropertyChanged(this, new PropertyChangedEventArgs(info)); });
        }
    }
}

Message Class

 public class Message 
{
    public string Text { get; set; }

}

Answer 1

There's an indirect but easier way to retrieve the content of the textblock.

In the click event, you can retrieve the object your model by using the DataContext property:

private void Copy_Click(object sender, RoutedEventArgs e)
{
    var model = (Message)((FrameworkElement)sender).DataContext;

    // Display model.Text in your TextBlock
}

Just replace Message by the type of the objects you've assigned to the ItemsSource of your listbox.