验证错误时保持对DatePicker的关注的最佳方法

Question

我找到了这个related question，它似乎（大部分）用于DataGridTextColumn中的TextBox。

如何为CellEditingTemplate中具有DatePicker的DataGridTemplateColumn实现类似的行为？
这段代码似乎无休止地被调用，这表明我们正在尝试将焦点设置为错误的元素：

private void DatePickerLostFocusHandler(object sender, RoutedEventArgs routedEventArgs)
    {  
     // What is the correct property to use here?
     // datePicker.GetBindingExpression(TextBox.TextProperty).UpdateSource();

        if (Validation.GetHasError(datePicker))
        {
            // Looks like this is setting focus to wrong element -- it ends up getting called repeatedly.

            var element = (sender as DatePicker);
            var restoreFocus = (System.Threading.ThreadStart)delegate { element.Focus(); };
            Dispatcher.BeginInvoke(restoreFocus);
        }
    }

感谢您的任何见解---