Get rid of the line under that tab of the tab control

Question

Using xaml ( wpf ) I'm trying to get rid of the line under the tab control as show in the "Illustration A" below so that it ends up looking like "Illustration B":

Illustration A

Illustration B

The line shows up when I define the Tab Item but appears to be attached to the Tab Control, as a result changing BorderThickness on either or both the Tab Item or Tab Control doesn't seem to yield the desired result.

I need to do this over a transparent background where a solid fill rectangle can't be used to mask the problem.

Here's the code:

<!--Tab Control-->
<Style  TargetType="{x:Type TabControl}">
    <Setter Property="OverridesDefaultStyle" Value="True" />
    <Setter Property="SnapsToDevicePixels" Value="True" />
     <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type TabControl}">
                <Grid KeyboardNavigation.TabNavigation="Local">
                    <Grid.RowDefinitions>
                        <RowDefinition Height="Auto"/>
                        <RowDefinition Height="*"/>
                    </Grid.RowDefinitions>
                    <TabPanel Name="HeaderPanel" Grid.Row="0" Panel.ZIndex="1" Margin="0,0,0,-1" IsItemsHost="True" KeyboardNavigation.TabIndex="1" Background="Transparent" />
                    <Border 
                        Name="Border" 
                        Grid.Row="1" 
                        Background="{StaticResource WindowBackgroundBrush}" 
                        BorderBrush="{StaticResource DefaultSystemBrush}" 
                        BorderThickness="1,1,1,1" 
                        Margin="0,0,0,0"
                        CornerRadius="4" 
                        KeyboardNavigation.TabNavigation="Local"
                        KeyboardNavigation.DirectionalNavigation="Contained"
                        KeyboardNavigation.TabIndex="2" >
                        <ContentPresenter 
                             Name="PART_SelectedContentHost"
                             Margin="4"
                             ContentSource="SelectedContent" />
                    </Border>                                         
                </Grid>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsEnabled" Value="False">
                        <Setter Property="Foreground" Value="{StaticResource DisabledForegroundBrush}" />
                        <Setter TargetName="Border" Property="BorderBrush" Value="{StaticResource DisabledBorderBrush}" />
                    </Trigger>
        <Trigger Property="IsEnabled" Value="False">
          <Setter Property="Foreground" Value="{StaticResource DisabledForegroundBrush}" />
          <Setter Property="BorderBrush" TargetName="Border" Value="{StaticResource DisabledBorderBrush}" />
        </Trigger>
      </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

<Style TargetType="{x:Type TabItem}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type TabItem}">
                <Grid>
                    <Border Name="Border" Background="Transparent" BorderBrush="{StaticResource DefaultSystemBrush}" BorderThickness="1,1,1,1" CornerRadius="6,6,0,0">
                        <ContentPresenter x:Name="ContentSite" VerticalAlignment="Center" HorizontalAlignment="Center" ContentSource="Header" Margin="12,2,12,2"/>
                    </Border>
                </Grid>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsSelected" Value="True">
                        <Setter Property="Panel.ZIndex" Value="100" />
                        <Setter TargetName="Border" Property="Background" Value="Transparent" />
                        <Setter TargetName="Border" Property="BorderThickness" Value="1,1,1,0" />
                    </Trigger>
                    <Trigger Property="IsSelected" Value="False">
                        <Setter TargetName="Border" Property="Background" Value="LightGray" />
                        <Setter TargetName="Border" Property="BorderThickness" Value="1,1,1,0" />
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

Thanks in advance,

Rob

Answer 1

Using ShowMeTheTemplate I found out part of the style, it's on the TabItem. There is a lot more in the default control template you may be interested in setting up if you override it.

<MultiTrigger>
  <MultiTrigger.Conditions>
    <Condition Property="Selector.IsSelected">
      <Condition.Value>
        <s:Boolean>True</s:Boolean>
      </Condition.Value>
    </Condition>
    <Condition Property="TabItem.TabStripPlacement" Value="{x:Static Dock.Top}" />
  </MultiTrigger.Conditions>
  <Setter Property="FrameworkElement.Margin">
    <Setter.Value>
      <Thickness>-2,-2,-2,-1</Thickness>
    </Setter.Value>
  </Setter>
</MultiTrigger>

Answer 2

You could always use Snoop to check it out, too. http://blois.us/blog/2006/08/long-time-since-my-last-post-but-dont_21.html