public static readonly DependencyProperty KeepAliveProperty =  DependencyProperty.Register(
"KeepAlive",
 typeof(bool),
 typeof(Window),
 new PropertyMetadata(KeepAliveChanged));

        /// <summary>

        /// 获取一个值，该值指示是否在现代化框架实例中保持指定对象的活动状态/// </summary>

        /// <param name="o">The target dependency object.</param>

        /// <returns>Whether to keep the object alive. Null to leave the decision to the ModernFrame.</returns>

        public static bool? GetKeepAlive(DependencyObject o)

        {

            if (o == null) {

                throw new ArgumentNullException("o");

            }

            return (bool?)o.GetValue(KeepAliveProperty);

        }

        /// <summary>

        /// 设置一个值，该值指示是否在现代化框架实例中保持指定对象的活动状态/// </summary>

        /// <param name="o">The target dependency object.</param>

        /// <param name="value">Whether to keep the object alive. Null to leave the decision to the ModernFrame.</param>

        public static void SetKeepAlive(DependencyObject o, bool? value)

        {

            if (o == null) {

                throw new ArgumentNullException("o");

            }

            o.SetValue(KeepAliveProperty, value);

        }

        private static void KeepAliveChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)

        {

            var window = d as Window;

            if (window != null)

            {

                window.DialogResult = e.NewValue as bool?;

            }

        }