关于#wpf#的问题：MenuItem 的CommandParameter怎么绑定Window对象

<Window x:Class="ModernBoxes.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:ModernBoxes"
        mc:Ignorable="d"
        WindowStartupLocation="CenterScreen"
        ResizeMode="NoResize"
        MouseLeftButtonDown="Grid_MouseLeftButtonDown"
        Background="Transparent"
        
        xmlns:hc="https://handyorg.github.io/handycontrol"
        
        x:Name="window"
        Title="MainWindow" Height="800" Width="800">
    <hc:Card hc:BorderElement.CornerRadius="20"  Background="White" Effect="{StaticResource EffectShadow1}">
        <hc:Card.ContextMenu>
            <ContextMenu>
                <MenuItem Header="展开"/>
                <MenuItem Header="收缩"/>
                <MenuItem Header="关闭" Command="{Binding WindowClose}" 
                          CommandParameter="{
                    Binding RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=ContextMenu}
                    ,Path=PlacementTarget}"/>
            </ContextMenu>
        </hc:Card.ContextMenu>

    </hc:Card>
</Window>

MenuItem 的CommandParameter怎么绑定Window对象