xaml style a border brush inside RibbonMenuItem - xaml

Question

Im trying to style a RibbonMenuItem target type. the items inside are checkmark with border and contents. When IsMouseOver i want the border brush to be black.
The problem is there's not a borderbrush on the menuitem trigger property, and also im assuming the IsHighLighted is sort of like IsMouseOver property, so i make a seperate border style, and bind it to the style under trigger. i even tried to set the Opacity to a 1 value, but nothing seems to work
this is my code, as you can tell, im trying to override the ribbonmenuitem style
<Style x:Key="BorderThicknessStyle"
TargetType="{x:Type Border}">
<Setter Property="BorderThickness" Value="1"/>
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="BorderThickness" Value="2"/>
</Trigger>
</Style.Triggers>
</Style>
<Style x:Key="{x:Type RibbonMenuItem}"
TargetType="{x:Type RibbonMenuItem}">
<Setter Property="HorizontalContentAlignment" Value="{Binding
Path=HorizontalContentAlignment,RelativeSource={RelativeSource AncestorType=
{x:Type ItemsControl}}}" />
<Setter Property="VerticalContentAlignment" Value="{Binding
Path=VerticalContentAlignment,RelativeSource={RelativeSource AncestorType=
{x:Type ItemsControl}}}" />
<Setter Property="Background" Value="Transparent" />
<Setter Property="BorderBrush" Value="Transparent" />
<Setter Property="BorderThickness" Value="1" />
<Setter Property="FocusVisualStyle" Value="{x:Null}" />
<Setter Property="Padding" Value="3,2,3,2" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type RibbonMenuItem}">
<Grid x:Name="MainGrid" SnapsToDevicePixels="True">
<Border x:Name="Border"
Background="{TemplateBinding Background}"
BorderThickness="{TemplateBinding
BorderThickness}"
BorderBrush="{TemplateBinding BorderBrush}"
CornerRadius="2">
<Grid>
<Grid.ColumnDefinitions>
<!--Icon or check mark column-->
<ColumnDefinition MinWidth="22"
Width="Auto"
SharedSizeGroup="MenuItemIconColumnGroup" />
<!--Header column-->
<ColumnDefinition Width="*"/>
<!--Submenu arrow column-->
<ColumnDefinition Width="14" />
</Grid.ColumnDefinitions>
<Border x:Name="PART_SideBarBorder"
BorderThickness="1"
Background="{DynamicResource
ThemeWindowBackgroundBrush}"
BorderBrush="{Binding RelativeSource=
{RelativeSource TemplatedParent},
Path=Ribbon.BorderBrush}"
MaxWidth="17"
MaxHeight="17">
<Grid x:Name="SideBarOverlay"
Background="{TemplateBinding
Background}">
<Image x:Name="Image"
Width="16"
Height="16"
Margin="4,3,6,1"
VerticalAlignment="Center"
HorizontalAlignment="Center"
Source="{TemplateBinding
ImageSource}" />
<Border x:Name="CheckMarkBorder"
BorderBrush="{TemplateBinding
BorderBrush}"
ClipToBounds="True">
<Path x:Name="CheckMark"
Visibility="Hidden"
Data="M 0 5 L 3 8 M 3 8 L 8 0"
Stretch="Uniform"
Stroke="{TemplateBinding
Foreground}"
StrokeEndLineCap="Round"
StrokeStartLineCap="Round"
Margin="2"
StrokeThickness="2" />
</Border>
</Grid>
</Border>
<ContentPresenter Grid.Column="1"
ContentSource="Header"
VerticalAlignment="Center"
Margin="{TemplateBinding Padding}"
RecognizesAccessKey="True" />
<Path x:Name="Arrow"
Visibility="Collapsed"
Grid.Column="2"
VerticalAlignment="Center"
HorizontalAlignment="Center"
Fill="{TemplateBinding Foreground}" />
</Grid>
</Border>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="ImageSource" Value="{x:Null}">
<Setter TargetName="Image" Property="Visibility"
Value="Collapsed" />
</Trigger>
<Trigger Property="IsCheckable" Value="True">
<Setter TargetName="Arrow" Property="Visibility"
Value="Hidden" />
</Trigger>
<Trigger Property="IsChecked" Value="True">
<Setter TargetName="CheckMark" Property="Visibility"
Value="Visible" />
<Setter TargetName="CheckMarkBorder"
Property="Visibility" Value="Visible" />
<Setter TargetName="Image" Property="Visibility"
Value="Hidden" />
</Trigger>
<Trigger Property="IsHighlighted" Value="True">
<Setter TargetName="PART_SideBarBorder"
Property="Style" Value="
{StaticResource BorderThicknessStyle}"/>
</Trigger>
<Trigger Property="IsEnabled" Value="False">
<Setter TargetName="Image" Property="Opacity"
Value="0.5" />
<Setter TargetName="Arrow" Property="Opacity"
Value="0.5" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>

Answer 1

This works for me. In the ControlTemplate.Triggers, you want to add the DataTrigger instead of Trigger.
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=IsHighlighted}"
Value="True">
<Setter TargetName="PART_SideBarBorder" Property="BorderBrush"
Value="Black"/>
</DataTrigger>