WPF:如何使用嵌套(分层)控件实现拖放

<Grid>
   <StackPanel x:Name="stackPanel" AllowDrop="True">
       <Button Content="Button1" />
       <Button Content="Button2" />
       <Button Content="Button3" />
    </StackPanel>
</Grid>

<DataTemplate x:Key="DraggedButtonTemplate">
   <Button Content="{Binding Content, RelativeSource={RelativeSource AncestorType=Button}}" />
</DataTemplate>

        MouseMove="Button_MouseMove"
        MouseLeftButtonUp="Button_MouseLeftButtonUp" />

private void Button_MouseMove(object sender, MouseEventArgs e)
{
    Button button = sender as Button;
    DataObject data = new DataObject(typeof(Button), button);
    DragDrop.DoDragDrop(button, data, DragDropEffects.Move);
}

private void Button_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
    Button button = sender as Button;
    DataObject data = new DataObject(typeof(Button), button);
    DragDrop.DoDragDrop(button, data, DragDropEffects.Move);
}

            AllowDrop="True"
            DragEnter="StackPanel_DragEnter"
            DragLeave="StackPanel_DragLeave"
            Drop="StackPanel_Drop" />

private void StackPanel_DragEnter(object sender, DragEventArgs e)
{
    if (e.Data.GetDataPresent(typeof(Button)))
    {
        e.Effects = DragDropEffects.Move;
    }
    else
    {
        e.Effects = DragDropEffects.None;
    }
}

private void StackPanel_DragLeave(object sender, DragEventArgs e)
{
    e.Effects = DragDropEffects.None;
}

private void StackPanel_Drop(object sender, DragEventArgs e)
{
    if (e.Data.GetDataPresent(typeof(Button)))
    {
        Button button = e.Data.GetData(typeof(Button)) as Button;
        Point point = e.GetPosition(stackPanel);
        button.RenderTransform = new TranslateTransform(point.X, point.Y);
        stackPanel.Children.Add(button);
    }
}