这是Windows窗体中的限制，您不能拥有超过屏幕最大尺寸20px的窗口。在设计时有一种解决方法，但是当你运行表单时，没有办法让它比你的屏幕更大。

This is a limitation in Windows Forms, you cannot have a window that is greater than 20px over the maximum dimensions of the screen. There is a way around this at design time, but when you run the form there is no way to make it bigger than your screen.