WPF中实现Expander标题的文字竖排

有时Expande 控件的标题文字需要竖排，例如 Expande的FlowDirection属性为"RightToLeft"，即左右方向的收缩：

<Grid x:Name="gridTemplate">
        <Grid.Resources>
        <!--模板数据的Expender标题竖排-->
         <DataTemplate x:Key="ExpanderHeaderTextV">
          <TextBlock Text="{Binding}" 
                   Width="30"
                   Foreground="Green" 
                   FontSize="20" 
                   FontWeight="Normal"
                   TextWrapping="Wrap">
                <TextBlock.RenderTransform>
                <TransformGroup>
              　　<MatrixTransform/>
                 </TransformGroup>
                </TextBlock.RenderTransform>  
                     <Run  Text="模"/>
                     <LineBreak/>
                     <Run Text="版"/>
                     <LineBreak/>
                     <Run Text="内"/>
                     <LineBreak/>
                     <Run Text="容"/>
                    <LineBreak/>
          </TextBlock>
         </DataTemplate>
      </Grid.Resources>
      <Expander HorizontalAlignment="Stretch" Header=""  HeaderTemplate="{StaticResource ExpanderHeaderTextV}" ExpandDirection="Left" 　　　　FlowDirection="RightToLeft" VerticalAlignment="Stretch" AllowDrop="False">
             <TabControl IsSynchronizedWithCurrentItem="True" Margin="0,0,0,0" FontSize="14">
                         <TabItem Header="模板数据" x:Name="tabTemplate">
                                   <Grid/>
                          </TabItem>
                                                                    
              </TabControl>
         </Expander>
</Grid>