Comment puis-je aligner verticalement un TextBox dans un StackPanel?

Dans le code XAML suivant, le mot "Test" centres de horizontalement mais pas verticalement.

Comment puis-je obtenir centrer verticalement?

<Window x:Class="TestVerticalAlign2343.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        WindowStartupLocation="CenterScreen"
    Title="Window1" Height="768" Width="1024">
    <DockPanel LastChildFill="True">
        <Slider x:Name="TheSlider"
                DockPanel.Dock="Left"
                Orientation="Vertical"
                HorizontalAlignment="Center"
                HorizontalContentAlignment="Center"
                Minimum="0"
                Maximum="10"
                Cursor="Hand"
                Value="{Binding CurrentSliderValue}"
                IsDirectionReversed="True"
                IsSnapToTickEnabled="True"
                Margin="10 10 0 10"/>
        <Border DockPanel.Dock="Right" Background="Beige"
                Padding="10"
                Margin="10"
                CornerRadius="5">
            <StackPanel Height="700">
                <TextBlock
                    Text="Test"
                    HorizontalAlignment="Center"
                    VerticalAlignment="Center"
                    FontSize="200" x:Name="TheNumber"/>

            </StackPanel>
        </Border>
    </DockPanel>
</Window>

source d'informationauteur Edward Tanguay