/// <summary>

        /// 阻止 alt+f4和alt+space 按键

        /// </summary>

        /// <param name="e"></param>

        protected override void OnKeyDown(System.Windows.Input.KeyEventArgs e)

        {

            if (Keyboard.Modifiers == ModifierKeys.Alt && e.SystemKey == Key.Space)

            {

                e.Handled = true;

            }

            else if (Keyboard.Modifiers == ModifierKeys.Alt && e.SystemKey == Key.F4)

            {

                e.Handled = true;

            }

            else

            {

                base.OnKeyDown(e);

            }

        }