如何在没有StaysOpen = false的情况下点击弹出窗口外关闭弹出窗口？

Question

XAML：

   <TextBox x:Name="textBox" GotFocus="textBox_GotFocus" LostFocus="textBox_LostFocus"/>
    <Popup x:Name="pop" StaysOpen="True" Placement="Bottom" IsOpen="True" PlacementTarget="{Binding ElementName=textBox}" Width="{Binding Width, ElementName=textBox}" >
        <TextBlock Background="White" Text="Some Message"/>
    </Popup>

关于我目前拥有的代码：

    private void textBox_GotFocus(object sender, RoutedEventArgs e)
    {
        pop.IsOpen = true;
    }

    private void textBox_LostFocus(object sender, RoutedEventArgs e)
    {
        pop.IsOpen = false;
    }

我想在文本框获得焦点时显示弹出窗口，直到其他任何地方被点击或文本框失去焦点为止。所以StaysOpen = false不起作用。经过大量搜索后，我查找了组合框的代码here

我认为以下代码是设置StaysOpen = false导致弹出窗口在弹出窗口外单击时关闭的原因。我不知道如何覆盖此行为。 以下代码的确切链接为here（为简洁起见，删除了注释）

private static void OnLostMouseCapture(object sender, MouseEventArgs e)
    {
        Popup popup = sender as Popup;
         if (!popup.StaysOpen)
        {
            PopupRoot root = popup._popupRoot.Value;
            bool reestablishCapture = e.OriginalSource != root && Mouse.Captured == null && MS.Win32.SafeNativeMethods.GetCapture() == IntPtr.Zero;

            if(reestablishCapture)
            {
                popup.EstablishPopupCapture();
                e.Handled = true;
            }
            else
            {
                if(Mouse.Captured != root)
                {
                    popup._cacheValid[(int)CacheBits.CaptureEngaged] = false;
                }

                bool newCaptureInsidePopup = Mouse.Captured != null && MenuBase.IsDescendant(root, Mouse.Captured as DependencyObject);
                bool newCaptureOutsidePopup = !newCaptureInsidePopup && Mouse.Captured != root;
                if(newCaptureOutsidePopup && !popup.IsDragDropActive)
                {
                    popup.SetCurrentValueInternal(IsOpenProperty, BooleanBoxes.FalseBox);
                }
            }
        }
    }