使用CWnd创建Dialog的关键代码段

class CCatchScreenWnd : public CWnd
{
public:
BOOL CreateEx();
protected:
virtual BOOL PreCreateWindow(CREATESTRUCT& cs);
DECLARE_MESSAGE_MAP()
};

BOOL CCatchScreenWnd::PreCreateWindow(CREATESTRUCT& cs)
{
if (!CWnd::PreCreateWindow(cs))  
   return   FALSE;  
   
cs.dwExStyle &= ~WS_EX_CLIENTEDGE; //去掉边框
cs.style &= ~WS_BORDER;  
cs.lpszClass = AfxRegisterWndClass(CS_HREDRAW | CS_VREDRAW | CS_DBLCLKS,    
      ::LoadCursor(NULL,IDC_ARROW),HBRUSH(COLOR_WINDOW+1), NULL);
}

BOOL CCatchScreenWnd::CreateEx()
{
BOOL bok = FALSE;
bok = CreateEx(WS_EX_TOPMOST,_T("ytCatchScreen"),
   NULL, WS_VISIBLE | WS_POPUP,0,0,0,0,NULL,NULL);
returen bok;
}