WPF, how to style TabItem basing on TabControl's property? - wpf

Question

I want to achieve similar effect, which can be seen in Notepad++: dividing TabContol into two TabControls. Obviously both will have selected tab on their own, but still only one of them will be active.
For those who doesn't know Notepad++, this is how it looks like:
For that I'll need to introduce "Active" property on TabControl (not Focused, because when one of TabControls loses focus, its selected tab still remains active). However, I have no idea how to craft trigger on TabItem's ControlTemplate, which will allow me to distinguish selected and selected+active tab.
This is how my current TabItem template look:
<Style x:Key="BaseRootTabItem" TargetType="TabItem">
<Style.Setters>
<Setter Property="Background" Value="{StaticResource NormalTabBackgroundBrush}" />
<Setter Property="TextBlock.Foreground" Value="{StaticResource NormalTabForegroundBrush}" />
</Style.Setters>
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Trigger.Setters>
<Setter Property="Background" Value="{StaticResource HoverTabBackgroundBrush}" />
<Setter Property="TextBlock.Foreground" Value="{StaticResource HoverTabForegroundBrush}" />
</Trigger.Setters>
</Trigger>
</Style.Triggers>
</Style>
<Style x:Key="DocumentTabItem" TargetType="TabItem" BasedOn="{StaticResource BaseRootTabItem}">
<Style.Setters>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="TabItem">
<Border x:Name="TabBorder" BorderThickness="1,1,1,0" BorderBrush="Transparent"
Background="{TemplateBinding Background}" TextBlock.Foreground="{TemplateBinding Foreground}">
<ContentPresenter x:Name="ContentSite" HorizontalAlignment="Center" VerticalAlignment="Center" ContentSource="Header" Margin="6,2" />
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style.Setters>
<Style.Triggers>
<Trigger Property="IsSelected" Value="True">
<Trigger.Setters>
<Setter Property="Background" Value="{StaticResource SelectedDocumentTabBackgroundBrush}" />
<Setter Property="Foreground" Value="{StaticResource SelectedDocumentTabForegroundBrush}" />
</Trigger.Setters>
</Trigger>
</Style.Triggers>
</Style>
I need something like:
<Trigger Property="(Owning TabControlEx's Active property)" Value="True">
<Trigger.Setters>
...
</Trigger.Setters>
</Trigger>
Or maybe there's some other solution?

Answer 1

Since Active property doesn't belong to TabItem, Trigger won't work. Use DataTrigger with binding to parent:
<DataTrigger Binding="{Binding Active, RelativeSource={RelativeSource AncestorType=TabControlEx}}"
Value="True">
</DataTrigger>