增加WPF PopUp动画的持续时间

<Popup Name="myPopup" IsOpen="False" AllowsTransparency="True" Placement="MousePoint">
   <Border Background="White" CornerRadius="5" Padding="10">
        <TextBlock FontSize="14" Text="这是一个Popup窗口！" />
    </Border>
</Popup>

private void ShowPopup()
{
    myPopup.IsOpen = true;
    myPopup.StaysOpen = false;

    // 设置动画持续时间为2秒
    DoubleAnimation animation = new DoubleAnimation(0, 200, new Duration(TimeSpan.FromSeconds(2)));
    myPopup.BeginAnimation(WidthProperty, animation);
}

private void Button_Click(object sender, RoutedEventArgs e)
{
    ShowPopup();
}