如何在 C# 中检测“外部”按键

我正在用Microsoft Visual Studio在C#中制作一个简单的应用程序。

应用程序使光标移动到一个点（窗体外窗口）并单击多次。我通过按 X 开始点击循环。因此，如果您有兴趣，代码如下所示：

public void Wait(int milliseconds)
        {
            System.Threading.Thread.Sleep(milliseconds);
        }
        [System.Runtime.InteropServices.DllImport("user32.dll")]
        public static extern void mouse_event(int dwFlags, int dx, int dy, int cButtons, int dwExtraInfo);
        public const int MOUSEEVENTF_LEFTDOWN = 0x02;
        public const int MOUSEEVENTF_LEFTUP = 0x04;
        public const int MOUSEEVENTF_RIGHTDOWN = 0x08;
        public const int MOUSEEVENTF_RIGHTUP = 0x10;
        public void MouseClick(Point pos, int click = 0)
        {
            int x = pos.X;
            int y = pos.Y;
            //MessageBox.Show("clicking mouse on " + pos.ToString());
            if (click == 1)
            {
                mouse_event(MOUSEEVENTF_RIGHTDOWN, x, y, 0, 0);
                mouse_event(MOUSEEVENTF_RIGHTUP, x, y, 0, 0);
            }
            else
            {
                mouse_event(MOUSEEVENTF_LEFTDOWN, x, y, 0, 0);
                mouse_event(MOUSEEVENTF_LEFTUP, x, y, 0, 0);
            }
        }
        public void MouseMove(int x, int y)
        {
            MouseMove(new Point(x,y));
        }
        public void MouseMove(Point target)
        {
            Cursor.Position = target;
        }
        private void Form1_KeyUp(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.A)
            {
                MessageBox.Show(Cursor.Position.ToString());
            }
            MouseMove(42, 42);
            if (e.KeyCode == Keys.X)
            {
                MessageBox.Show(Cursor.Position.ToString());            
                Wait(42);
                Random r = new Random();
                for (int i = 0; i < number_of_times ; i++)
                {
                    Wait(r.Next(42));
                    MouseClick(Cursor.Position);
                }
            }
        }

但是，如您所见，单击开始后，表单将返回（在屏幕上不可见），因此无法检测到按键。那么我怎样才能停止点击循环呢？如果我执行 Ctrl + Alt + Del，它会暂停，然后我打开任务管理器，但单击继续。

也许有一种检测ctrl alt del的方法？ 或任何其他按键，当窗口关闭时？

感谢您的任何帮助！