C / C++ / MFC

--------
A.h
--------
class A: public CStatic
{
    ... ... // other codes

	// Generated message map functions
protected:
	//{{AFX_MSG(CEMap)
	afx_msg void OnPaint();
	afx_msg BOOL OnEraseBkgnd(CDC* pDC);
	afx_msg void OnSize(UINT nType, int cx, int cy);
	afx_msg void OnWindowPosChanged(WINDOWPOS FAR* lpwndpos);
	afx_msg void OnLButtonDown(UINT nFlags, CPoint point);
	afx_msg void OnLButtonDblClk(UINT nFlags, CPoint point);
	afx_msg void OnMouseMove(UINT nFlags, CPoint point);
	afx_msg void OnLButtonUp(UINT nFlags, CPoint point);
	afx_msg int OnCreate(LPCREATESTRUCT lpCreateStruct);
	//}}AFX_MSG

	afx_msg	BOOL OnDrop(WPARAM pDropInfoClass, LPARAM lParm);
	afx_msg	DROPEFFECT OnDropEx(WPARAM pDropInfoClass, LPARAM lParm);
	afx_msg	DROPEFFECT OnDragOver(WPARAM pDropInfoClass, LPARAM lParm);

	DECLARE_MESSAGE_MAP()

protected:
    COleDropTargetEx   m_dropEx;
    static WORD s_wNvrChnClipboardFormat;

    ... ... // other codes

}

----
A.cpp
----
WORD A::s_wNvrChnClipboardFormat = 0X0;

BEGIN_MESSAGE_MAP(A, CStatic)
	//{{AFX_MSG_MAP(A)
	ON_WM_PAINT()
	ON_WM_ERASEBKGND()
	ON_WM_SIZE()
	ON_WM_WINDOWPOSCHANGED()
	ON_WM_LBUTTONDOWN()
	ON_WM_LBUTTONDBLCLK()
	ON_WM_MOUSEMOVE()
	ON_WM_LBUTTONUP()
	ON_WM_CREATE()
	//}}AFX_MSG_MAP

	ON_MESSAGE(DROPM_DRAGOVER,OnDragOver)
	ON_MESSAGE(DROPM_DROPEX,OnDropEx)
	ON_MESSAGE(DROPM_DROP,OnDrop)

END_MESSAGE_MAP()

int A::OnCreate(LPCREATESTRUCT lpCreateStruct) 
{
	if (CStatic::OnCreate(lpCreateStruct) == -1)
		return -1;	
        s_wNvrChnClipboardFormat = RegisterClipboardFormat(NAME_NC_NVRCHN_CLPFMT);	
	BOOL bRet = m_dropEx.Register (this);
	ASSERT(bRet);
	return 0;
}

// OnDragOver cannot be executed 
DROPEFFECT A::OnDragOver(WPARAM pDropInfoClass,LPARAM lParm)
{
	COleDropInfo* pInfo = (COleDropInfo* )pDropInfoClass;
	ASSERT(pInfo->IsKindOf(RUNTIME_CLASS(COleDropInfo)));

	if( pInfo->m_pDataObject->IsDataAvailable(s_wNvrChnClipboardFormat) )
		return DROPEFFECT_COPY;
	else
		return DROPEFFECT_NONE;
}

// OnDropEx cannot be executed 
DROPEFFECT A::OnDropEx(WPARAM pDropInfoClass, LPARAM lParm)
{
    return (DROPEFFECT)-1;
}