当MenuItem被禁用时，其中的TextBlock不会变成灰色。

我们可以自定义 MenuItem 的模板，使用触发器来改变 TextBlock 的颜色。具体实现代码如下：

<Window.Resources>
    <SolidColorBrush x:Key="DisabledForegroundBrush" Color="Gray"/>
    <ControlTemplate x:Key="MenuItemControlTemplate1" TargetType="{x:Type MenuItem}">
        <Border x:Name="Border" BorderThickness="1" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" SnapsToDevicePixels="True">
            <Grid>
                <ContentPresenter x:Name="Icon" Content="{TemplateBinding Icon}" Margin="4,0,6,0" VerticalAlignment="Center" Width="18" Height="18" RenderOptions.BitmapScalingMode="HighQuality"/>
                <TextBlock x:Name="Text" Text="{TemplateBinding Header}" Margin="4,0,6,0" VerticalAlignment="Center" Foreground="{TemplateBinding Foreground}"/>
                <TextBlock x:Name="InputGestureText" Text="{TemplateBinding InputGestureText}" Margin="0,0,6,0" VerticalAlignment="Center" Visibility="Collapsed" Foreground="{TemplateBinding Foreground}"/>
                <TextBlock x:Name="Text2" Text="{TemplateBinding Header}" Margin="4,0,6,0" VerticalAlignment="Center" Foreground="{StaticResource DisabledForegroundBrush}">
                    <TextBlock.Style>
                        <Style TargetType="TextBlock">
                            <Style.Triggers>
                                <DataTrigger Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type MenuItem}}, Path=IsEnabled}" Value="False">
                                    <Setter Property="Foreground" Value="{StaticResource DisabledForegroundBrush}"/>
                                </DataTrigger>
                            </Style.Triggers>
                        </Style>
                    </TextBlock.Style>
                </TextBlock>
            </Grid>
        </Border>
        <ControlTemplate.Triggers>
            <Trigger Property="IsSuspendingPopupAnimation" Value="True">
                <Setter TargetName="Popup" Property="PopupAnimation" Value="None"/>
            </Trigger>
            <Trigger Property="Icon" Value="{x:Null}">
                <Setter TargetName="Icon" Property="Visibility" Value