SeparatorBrush, SeparatorVisibility 속성을 이용해서 border에 구현할수있다.
아래의 코드에서 Rectangle을 만들고 fill과 visibility를 위의 속성에 바인딩 해주면
색으로 구분하는 걸 구현할수있다.
</Grid.ColumnDefinitions>
<Border x:Name="HeaderBorder"
Grid.Column="0"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Background="{TemplateBinding Background}"
Padding="{TemplateBinding Padding}">
<ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
RecognizesAccessKey="True"
SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}">
<ContentPresenter.Content>
<TextBlock Text="{Binding Content, RelativeSource={RelativeSource TemplatedParent}}"
TextAlignment="Center"
TextWrapping="Wrap" />
</ContentPresenter.Content>
</ContentPresenter>
</Border>
<Rectangle x:Name="SeparatorRectangle"
Grid.Column="1"
Width="1"
Fill="{TemplateBinding SeparatorBrush}"
Visibility="{TemplateBinding SeparatorVisibility}" />