wpf - トリガーでボタン コンテンツのフォアグラウンドを変更するにはどうすればよいですか?

Question

ボタンを押したときにトリガーからフォアグラウンドを変更したいのですが、これまでに持っている XAML は次のとおりです。

   <Window.Resources>
    <SolidColorBrush x:Key="FocuseBorder" Color="DarkBlue" ></SolidColorBrush>
    <SolidColorBrush x:Key="OverBorder" Color="Blue" />
    <SolidColorBrush x:Key="PressdBorder" Color="Red" />
    <SolidColorBrush  x:Key="DefulateBorder" Color="Black" ></SolidColorBrush>


    <LinearGradientBrush x:Key="GradDefulat" StartPoint="0.5,0" EndPoint="0.5,1">
        <GradientStop Color="#FF949494" Offset="0"/>
        <GradientStop Color="Black" Offset="1"/>
    </LinearGradientBrush>


    <LinearGradientBrush x:Key="GradOver" StartPoint="0.5,0" EndPoint="0.5,1">
        <GradientStop Color="Black" Offset="0"/>
        <GradientStop Color="#FF949494" Offset="1"/>
    </LinearGradientBrush>


    <LinearGradientBrush x:Key="GradPressd" StartPoint="0.5,0" EndPoint="0.5,1">
        <GradientStop Color="#FF666868" Offset="0"/>
        <GradientStop Color="Black" Offset="1"/>
    </LinearGradientBrush>


    <LinearGradientBrush x:Key="GradFocuse" StartPoint="0.5,0" EndPoint="0.5,1">
        <GradientStop Color="White" Offset="0"/>
        <GradientStop  Color="#FF5F5F5F" Offset="1"/>
    </LinearGradientBrush>

    <Style x:Key="SelectionButton3"
    TargetType="{x:Type Button}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type Button}">

                    <Grid Name="grd" HorizontalAlignment="Stretch"
                    VerticalAlignment="Stretch"
                    ClipToBounds="False">
                        <Border x:Name="TheBorder" CornerRadius="10"  
                        Background="{StaticResource GradDefulat}"   Height="{Binding Path=Height}" Width="{Binding Path=Width}"
                        BorderBrush="DarkSlateBlue"> </Border>
                        <Rectangle Name="rect" Fill="{StaticResource GradDefulat}"  Stroke="DarkSlateBlue"
                         Height="200" Width="50"> 
                            <Rectangle.RenderTransform >
                                <RotateTransform Angle="45" CenterX=" 30" CenterY="25" >  
                                </RotateTransform>
                            </Rectangle.RenderTransform>
                        </Rectangle>
                        <ContentPresenter x:Name="ContentArea" VerticalAlignment="Center"   HorizontalAlignment="Center "
                                    Content="{Binding Path=Content, RelativeSource={RelativeSource TemplatedParent}}" />
                    </Grid>
                    <ControlTemplate.Triggers >

                        <Trigger Property="IsDefaulted" Value="True">
                            <Setter TargetName="TheBorder" Property ="Background" Value="{StaticResource GradDefulat}"/>
                            <Setter TargetName="TheBorder" Property="BorderBrush" Value="{StaticResource DefulateBorder}"/>
                            <Setter TargetName="rect" Property ="Fill" Value="{StaticResource GradDefulat}"/>
                            <Setter TargetName="rect" Property="Stroke" Value="{StaticResource DefulateBorder}"/>

                        </Trigger>
                        <!-- Defaulated-->

                        <Trigger Property="IsMouseOver" Value="True">
                            <Setter TargetName="TheBorder" Property="Background" Value="{StaticResource GradOver}"/>
                            <Setter TargetName="TheBorder" Property="BorderBrush" Value="{StaticResource OverBorder}"/>
                            <Setter TargetName="rect" Property="Fill" Value="{StaticResource GradOver}"/>
                            <Setter TargetName="rect" Property="Stroke" Value="{StaticResource OverBorder}"/>
                        </Trigger>
                        <!-- Over-->

                        <Trigger Property="IsFocused" Value="True">
                            <Setter TargetName="TheBorder" Property="Background" Value="{StaticResource GradFocuse}"/>
                            <Setter TargetName="TheBorder" Property="BorderBrush" Value="{StaticResource FocuseBorder}"/>
                            <Setter TargetName="rect" Property="Fill" Value="{StaticResource GradFocuse}"/>
                            <Setter TargetName="rect" Property="Stroke" Value="{StaticResource FocuseBorder}"/>
                        </Trigger>
                        <!--Focuse-->

                        <Trigger Property="IsPressed" Value="True">
                            <Setter TargetName="TheBorder" Property="Background" Value="{StaticResource GradPressd}"/>
                            <Setter TargetName="TheBorder" Property="BorderBrush" Value="{StaticResource PressdBorder}"/>
                            <Setter TargetName="rect" Property="Fill" Value="{StaticResource GradPressd}"/>
                            <Setter TargetName="rect" Property="Stroke" Value="{StaticResource PressdBorder}"/>
                        </Trigger>
                        <!-- Focuse-->
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

</Window.Resources> 

英語は私の母国語ではないので、詳細が不足していることをお詫びします。