fixed cut,copy,paste with splitter

BEGIN_MSG_MAP(CMainFrame)
        MESSAGE_HANDLER(WM_CREATE, OnCreate)
        MESSAGE_HANDLER(WM_DESTROY, OnDestroy)
        MESSAGE_HANDLER(WM_SETFOCUS, OnSetFocus)
        COMMAND_ID_HANDLER(ID_APP_EXIT, OnFileExit)
        COMMAND_ID_HANDLER(ID_FILE_NEW, OnFileNew)
    {
        int nPane = m_split.GetActivePane();
        if (nPane == SPLIT_PANE_LEFT)
            CHAIN_MSG_MAP_MEMBER(m_view)
        else
            CHAIN_MSG_MAP_MEMBER(m_edit)
    }

        CHAIN_MSG_MAP(CUpdateUI<CMainFrame>)
        CHAIN_MSG_MAP(CFrameWindowImpl<CMainFrame>)
    END_MSG_MAP()