SendMessage 笔记

void CCFileDialogDlg::OnButton()
{
 CWnd* hwnd = (CWnd*)GetDlgItem(IDCANCEL); //获取控件的指针；
 HWND H = hwnd->m_hWnd; //再获取控件的句柄；
 hwnd->SendMessage(BM_CLICK,0,0); 
 ::SendMessage(H,BM_CLICK,0,0);
}

SDK的SendMessage参数个数是四个
MFC的SendMessage参数个数是三个