(AFX_PMSG)(AFX_PMSGW)(void (AFX_MSG_CALL CWnd:)(UINT, CPoint))&OnLButtonDown,该怎么解决

(AFX_PMSG)(AFX_PMSGW)(void (AFX_MSG_CALL CWnd::*)(UINT, CPoint))&OnLButtonDown
#define ON_WM_LBUTTONDOWN() \
{ WM_LBUTTONDOWN, 0, 0, 0, AfxSig_vwp, \
(AFX_PMSG)(AFX_PMSGW)(void (AFX_MSG_CALL CWnd::*)(UINT, CPoint))&OnLButtonDown }


(AFX_PMSG)(AFX_PMSGW)(void (AFX_MSG_CALL CWnd::*)(UINT, CPoint))&OnLButtonDown
这句加上&OnLButtonDown怎么理解

------解决方案--------------------
取函数的指针？地址？