说明：  vc自定义消息的发送与接收的方法实现 以下用一个自创的对话框类(MyMessageDlg)向视图类(MessageTestView) 发送自定义消息为例，说明这两种不同方法的自定义消息的
(Implementation of VC custom message sending and receiving method The following with a dialog class (MyMessageDlg) to the view class (MessageTestView) Send a custom message as an example to illustrate the custom messages for these two different methods.)