启动自定义消息框时，我应该怎么做才能冻结父线程

我使用Coding4Fun工具包中的MessagePrompt创建了自定义MessageBox。当我运行ResetData_Click时出现问题。我希望在启动ComplexMessage.Show内部的其余代码后ResetData_Click在ComplexMessage打开时停止执行。正如发生的那样，情况完全不同。所有代码一次执行，用户在ComplexMessage中选择什么并不重要，因为

if (ComplexMessage.Result)...

已执行。我应该怎么做才能让我的ComplexMessage表现得像System.Windos.MessageBox？这意味着当调用MessageBox时，父线程正在等待用户的决定。

        private void ResetData_Click(object sender, RoutedEventArgs e)
        {
            ComplexMessage.Show("You are about to delete all data", "Are you sure?", true);
            if (ComplexMessage.Result)
            {
                DataControl.DataFileReset();
            }
        }
 public class ComplexMessage
    {
        private static MessagePrompt messageprompt;
        private static bool messageresult;
        public static void Show(string message, string title, bool vibrate)
        {
            if (!(!(messageprompt == null) && messageprompt.IsOpen))
            {
                messageprompt = new MessagePrompt
                {
                    Title = title,
                    Message = message
                };
                messageprompt.Completed += new EventHandler<PopUpEventArgs<string, PopUpResult>>(messageprompt_Completed);
                messageprompt.IsCancelVisible = true;
                messageprompt.Show();
                if (vibrate) { Tools.VibrateMessage(); }
            }
        }
        static void messageprompt_Completed(object sender, PopUpEventArgs<string, PopUpResult> e)
        {
            if (!e.PopUpResult.Equals(PopUpResult.Cancelled))
            {
                messageresult = true;
            }
            else
            {
                messageresult = false;
            }
            ((MessagePrompt)sender).Completed -= messageprompt_Completed;
        }
        public static bool Result
        {
            get { return messageresult; }
        }
    }