1、新建一个SHOW名称的对话框文件

2、在SHOWDlg.h中添加代码

#define WM_Display (WM_USER+100)

afx_msg LRESULT OnDisplay(WPARAM wParam, LPARAM lParam);

3、在SHOWDlg.cpp中添加代码

BEGIN_MESSAGE_MAP(CSHOWDlg, CDialog)
	...
	 ON_MESSAGE(WM_Display, OnDisplay)
END_MESSAGE_MAP()

BOOL CSHOWDlg::OnInitDialog()
{
	CDialog::OnInitDialog();
	::PostMessage(GetSafeHwnd(),WM_Display,0,0);
	...	
	return TRUE;  // return TRUE  unless you set the focus to a control
}

LRESULT CSHOWDlg::OnDisplay(WPARAM wParam, LPARAM lParam)
{
  //MessageBox("recv msg success");
  //添加自己的消息处理
 MessageBox("WM_USER_message");
  return 0;  
}

3、运行程序