如何为ContentPresenter Panel.ZIndex属性设置动画？

Question

我<ItemsControl>为我的<custom:Pack>列表创建了视图：

<ItemsControl ItemsSource="{Binding List}">
    <ItemsControl.ItemsPanel>
        <ItemsPanelTemplate>
            <local:ShelfPanel />
        </ItemsPanelTemplate>
    </ItemsControl.ItemsPanel>
    <ItemsControl.ItemContainerStyle>
        <Style>
            <Setter Property="local:ShelfPanel.Exact" Value="{Binding Exact}"/>
            // Default ZIndex is set 1, when Active it should be higher, hence will be over others.
            <Setter Property="Panel.ZIndex" Value="1" />
        </Style>
    </ItemsControl.ItemContainerStyle>
    <ItemsControl.ItemTemplate>
        <DataTemplate>
            <custom:Pack Background="Red" Width="150" Height="150" >
                <VisualStateManager.VisualStateGroups>
                    <VisualStateGroup x:Name="MyStates">
                        <VisualState x:Name="Normal" />
                        <VisualState x:Name="Selected">
                            <Storyboard>
                                <ColorAnimation Storyboard.TargetProperty="(Control.Background).(SolidColorBrush.Color)" To="Yellow" Duration="0:0:0.5" />
                            </Storyboard>
                        </VisualState>
                        <VisualState x:Name="Active">
                            <Storyboard>
                                <ColorAnimation Storyboard.TargetProperty="(Control.Background).(SolidColorBrush.Color)" To="Green" Duration="0:0:0.5" />
                                // How to animate ZIndex on ContentPresenter ?
                                <Int32Animation Storyboard.TargetProperty="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type ContentPresenter}}, Path=(Panel.ZIndex)}" To="3" Duration="00:00:0.2"/>
                            </Storyboard>
                        </VisualState>
                    </VisualStateGroup>
                </VisualStateManager.VisualStateGroups>
            </custom:Pack>
        </DataTemplate>
    </ItemsControl.ItemTemplate>
</ItemsControl>

<local:ShelfPanel>的设计方式<custom:Pack>相互重叠。现在，当您选择一个<custom:Pack>时，它的状态更改为Active，对象应该超过所有其他状态。 现在我得到了预期：

  

您必须为＆＃34; System.Windows.Media.Animation.Int32动画指定TargetProperty

要实现这一点，我需要在ContentPresenter上设置ZInedx，该怎么做？