TabItem样式如下：
<Style x:Key="TabItemExWithUnderLineStyle" TargetType="{x:Type TabItem}">
<Setter Property="Foreground" Value="White"/>
<Setter Property="Background" Value="Transparent"/>
<Setter Property="BorderBrush" Value="#FFACACAC"/>
<Setter Property="Margin" Value="0"/>
<Setter Property="HorizontalContentAlignment" Value="Stretch"/>
<Setter Property="VerticalContentAlignment" Value="Stretch"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TabItem}">
<Grid x:Name="templateRoot" SnapsToDevicePixels="True" Background="Transparent">
<Border x:Name="_underline" BorderBrush="#37aefe" BorderThickness="0" Margin="{TemplateBinding Margin}"/>
<Grid>
<TextBlock x:Name="txt" Visibility="Visible" VerticalAlignment="Center" HorizontalAlignment="Center" Text="{TemplateBinding Header}" ToolTip="{TemplateBinding Header}" Foreground="{TemplateBinding Foreground}" TextTrimming="CharacterEllipsis" />
</Grid>
</Grid>
<ControlTemplate.Triggers>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding IsMouseOver, RelativeSource={RelativeSource Self}}" Value="true"/>
<Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource FindAncestor, AncestorLevel=1, AncestorType={x:Type TabControl}}}" Value="Top"/>
</MultiDataTrigger.Conditions>
<Setter Property="Foreground" TargetName="txt" Value="#37aefe"/>
</MultiDataTrigger>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding IsEnabled, RelativeSource={RelativeSource Self}}" Value="false"/>
<Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource FindAncestor, AncestorLevel=1, AncestorType={x:Type TabControl}}}" Value="Left"/>
</MultiDataTrigger.Conditions>
<Setter Property="Opacity" TargetName="templateRoot" Value="0.56"/>
</MultiDataTrigger>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding IsEnabled, RelativeSource={RelativeSource Self}}" Value="false"/>
<Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource FindAncestor, AncestorLevel=1, AncestorType={x:Type TabControl}}}" Value="Bottom"/>
</MultiDataTrigger.Conditions>
<Setter Property="Opacity" TargetName="templateRoot" Value="0.56"/>
</MultiDataTrigger>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding IsEnabled, RelativeSource={RelativeSource Self}}" Value="false"/>
<Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource FindAncestor, AncestorLevel=1, AncestorType={x:Type TabControl}}}" Value="Right"/>
</MultiDataTrigger.Conditions>
<Setter Property="Opacity" TargetName="templateRoot" Value="0.56"/>
</MultiDataTrigger>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding IsEnabled, RelativeSource={RelativeSource Self}}" Value="false"/>
<Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource FindAncestor, AncestorLevel=1, AncestorType={x:Type TabControl}}}" Value="Top"/>
</MultiDataTrigger.Conditions>
<Setter Property="Opacity" TargetName="templateRoot" Value="0.56"/>
</MultiDataTrigger>
<MultiDataTrigger>
<MultiDataTrigger.Conditions>
<Condition Binding="{Binding IsSelected, RelativeSource={RelativeSource Self}}" Value="true"/>
<Condition Binding="{Binding TabStripPlacement, RelativeSource={RelativeSource FindAncestor, AncestorLevel=1, AncestorType={x:Type TabControl}}}" Value="Top"/> </MultiDataTrigger.Conditions>
<Setter Property="Panel.ZIndex" Value="1"/>
<Setter Property="Foreground" TargetName="txt" Value="#37aefe"/>
<Setter Property="BorderThickness" TargetName="_underline" Value="0 0 0 2"/>
</MultiDataTrigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
