我必须在单击按钮（打开弹出窗口）时打开一个弹出窗口，然后在单击按钮（打开内容对话框）时从弹出窗口中显示一个内容对话框。
如果我设置Popup.ShouldConstrainToRootBounds=false，内容对话框将显示在弹出窗口下方。我不明白发生了什么。我想在弹出窗口上方显示ContentDialog吗？
我的完整项目链接--〉Source Code
我的源代码：
XAML：

<Grid x:Name="Grid">
    <Button Click="Button_Click">Open Popup</Button>
</Grid>

C#：

private void Button_Click(object sender, RoutedEventArgs e)
{
        popup = new Popup {  Margin = new Thickness(200, 300, 0, 0),ShouldConstrainToRootBounds=false };
        Border border = new Border { Width = 400, Height = 300, Background = new SolidColorBrush(Colors.Green) };
        Button popupButton= new Button { Content = "Open Content Dialog", Width = 200, Height = 50 };
        border.Child = popupButton;
        popupButton.Click += PopupButton_Click;
        popup.Child = border;
        popup.IsOpen = true;
}

    private async void PopupButton_Click(object sender, RoutedEventArgs e)
    {
        ContentDialog contentDialog = new ContentDialog
        {
            Title = "ContentDialogOverPopup",
            Content = "Content Dialog",
            CloseButtonText = "Ok"
        };
        await contentDialog.ShowAsync();
    }