Set tooltip on customized tab header in WPF

<UserControl>   <UserControl.Resources>      <ResourceDictionary>         <ResourceDictionary.MergedDictionaries>            <ResourceDictionary Source="TextBlocks.xaml"/>         </ResourceDictionary.MergedDictionaries>        </ResourceDictionary>   </UserControl.Resources>  <TabItem><TabItem.Header>   <TextBlock Style="{StaticResource TabItemHeaderStyle}" Text="xxx" ToolTip="xxx"/></TabItem.Header></TabItem></UserControl>

in TextBlocks.xaml, customize header style for selection behaviour.

<ResourceDictionary     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">   <Style x:Key="TabItemHeaderStyle" TargetType="{x:Type TextBlock}">      <Style.Triggers>         <DataTrigger Binding="{Binding IsSelected, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type TabItem}}}" Value="True">            <Setter Property="Foreground" Value="#1fa5d8"/>            <Setter Property="FontWeight" Value="Bold"/>         </DataTrigger>         <DataTrigger Binding="{Binding IsSelected, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type TabItem}}}" Value="False">            <Setter Property="Foreground" Value="#4c4c4c"/>            <Setter Property="FontWeight" Value="Normal"/>         </DataTrigger>      </Style.Triggers>   </Style></ResourceDictionary>