right Syntax from inside a ComboBox Template to a property of the current Selected Item

Question

Hello,

i ma inside a comboBox Template and try to set a value inside to bind after the Current selectedItem, but missing the right Syntax for that maztter as may possible to write: Typogrpahy.Capitals={Binding Typorgraphy.Capitals, RelativeSoiurce={SelectedItem}}".. Das indeed wrong and not works,, but how to wrtie that ohrase in a right matter?

Here a code example,, the text line i try to get the right syntax is inside the TextBlock element,, marked with two stars

 <ComboBox FocusVisualStyle="{x:Null}" Text="C"  ToolTipService.ShowDuration="20000"  ToolTip="Capitals are a set of typographical forms that render text in capital-styled glyphs.&#x0d;Typically, when text is rendered as all capitals, the spacing between letters can appear too tight,&#x0d;and the weight and proportion of the letters too heavy.&#x0d;OpenType supports a number of styling formats for capitals,&#x0d;including small capitals, petite capitals, titling, and capital spacing.&#x0d;These styling formats allow you to control the appearance of capitals." Width="32" Height="32" FontFamily="Palatino Linotype" Grid.IsSharedSizeScope="True" x:Name="FontCapitalsComboBox"  Grid.ColumnSpan="2">  
                            <ComboBox.Resources>  
                                <Style TargetType="ComboBox" BasedOn="{StaticResource {x:Type ComboBox}}">  
                                    <Setter Property="Template">  
                                        <Setter.Value>  
                                            <ControlTemplate TargetType="ComboBox">  
                                                <Border  x:Name="Border" BorderThickness="1" BorderBrush="{StaticResource TypographyFieldBorderBrush}"  Background="{StaticResource ComboBoxOverlayBrush}">  
                                                    <Grid  x:Name="root" Background="Transparent">  
                                                        <TextBlock **Typography.CapitalSpacing="{Binding SelectedItem.Typography.CapitalSpacing}"**  Foreground="{StaticResource ToogelButtonComboBoxForegroundBrush}" FontSize="24" Padding="0" Text="{TemplateBinding Text}" IsHitTestVisible="False" HorizontalAlignment="Center" VerticalAlignment="Center"/>  
                                                        <TextBox x:Name="PART_EditableTextBox"  Visibility="Collapsed" IsReadOnly="true" />  
                                                        <Popup  x:Name="Popup" Placement="Bottom" IsOpen="{TemplateBinding IsDropDownOpen}" AllowsTransparency="True" Focusable="False" PopupAnimation="Slide">  
                                                            <Grid x:Name="DropDown" SnapsToDevicePixels="True"  MinWidth="{TemplateBinding ActualWidth}" MaxHeight="{TemplateBinding MaxDropDownHeight}">  
                                                                <Border x:Name="DropDownBorder" BorderThickness="1">  
                                                                    <Border.BorderBrush>  
                                                                        <SolidColorBrush Color="{DynamicResource BorderBrushColor}" />  
                                                                    </Border.BorderBrush>  
                                                                    <Border.Background>  
                                                                        <SolidColorBrush Color="{DynamicResource BackgroundColor}" />  
                                                                    </Border.Background>  
                                                                </Border>  
                                                                <ScrollViewer  Margin="4,6,4,6" SnapsToDevicePixels="True">  
                                                                    <StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained" />  
                                                                </ScrollViewer>  
                                                            </Grid>  
                                                        </Popup>  
                                                    </Grid>  
                                                </Border>  
                                            </ControlTemplate>  
                                        </Setter.Value>  
                                    </Setter>  
                                    <EventSetter Event="PreviewMouseLeftButtonDown" Handler="ComboBox_PreviewMouseLeftButtonDown"/>  
                                </Style>  
                             </ComboBox.Resources>  
                                <ComboBoxItem Typography.Capitals="Normal"  Content="Normal" Tag="Capital letters render normally."/>  
                                <ComboBoxItem Typography.Capitals="SmallCaps" Content="SmallCaps" Tag="Lowercase letters are replaced with a glyph form&#x0d;of an uppercase letter with the same approximate height."/>  
                                <ComboBoxItem Typography.Capitals="PetiteCaps" Content="PetiteCaps" Tag="Lowercase letters are replaced with a glyph form&#x0d;of an uppercase letter with the same approximate height.&#x0d;Petite capitals are smaller than small capitals."/>  
                                <ComboBoxItem Typography.Capitals="AllSmallCaps" Content="AllSmallCaps" Tag="Both capital and lowercase letters are replaced with a glyph&#x0d;form of an uppercase letter with the same approximate height."/>  
                                <ComboBoxItem Typography.Capitals="AllPetiteCaps" Content="AllPetiteCaps  " Tag="Both capital and lowercase letters are replaced with a glyph&#x0d;form of an uppercase letter with the same approximate height.&#x0d;Petite capitals are smaller than small capitals."/>  
                                <ComboBoxItem Typography.Capitals="Titling" Content="Titling" Tag="Glyph forms are substituted with a typographic form&#x0d;specifically designed for titles."/>  
                                <ComboBoxItem Typography.Capitals="Unicase" Content="Unicase" Tag="Capital letters display in unicase. Unicase fonts render both&#x0d;upper and lowercase letters in a mixture of upper and&#x0d;lowercase glyphs determined by the type designer."/>  
                            </ComboBox>