private void StepExecuted(object sender, ExecutedRoutedEventArgs e)
        {
            IconBar.MakeNextPCVisible();

            if (controller.Mode == PICControllerMode.PAUSED)
            {
                controller.Step();
            }
            else if (controller.Mode == PICControllerMode.WAITING)
            {
                controller.StartPaused();
            }
        }