Problem in expander toggle button in wpf

Hi,

      I want to put toggle button in right hand side but expender header in left hand side..i used flow direction but expander header also viewed in right side... please help me..

My coding....

<Page.Resources>
        <Style TargetType="{x:Type Expander}">
            <Setter Property="BorderThickness" Value="1"/>
            <Setter Property="BorderBrush" Value="DarkGray"/>
            <Setter Property="Foreground" Value="#202020"/>
            <Setter Property="Background" Value="#D0D0D0"/>
        </Style>
    </Page.Resources>
    <StackPanel>
        
        <Expander Width="200"
              Margin="0,8,0,0"
              Header="This is the Header">
            <Border Height="100">
                <StackPanel>
                    <TextBlock>TextBlock text</TextBlock>
                    <Label>Label text</Label>
                    <Label IsEnabled="False">Disabled label</Label>
                </StackPanel>
            </Border>
        </Expander>
    </StackPanel>