How to attach an render behavior to anchor object

I want to draw a border for element under the mouse, like the feature
in IE develeoper Toolbar, I attach a binary behavior to the element ,
but it don't work on anchor object (<a href="">test</a>), what is the
reason?

my source code :

class ATL_NO_VTABLE CBehavior :
public CComObjectRootEx<CComSingleThreadModel>,
public CComCoClass<CBehavior, &CLSID_Behavior>,
public IDispatchImpl<IBehavior, &IID_IBehavior, &LIBID_RENDERLib>,
public IElementBehavior,
public IHTMLPainter
{
public:

/
***********************************************************************************
******************** anchor object don't call this method
*********************
/
***********************************************************************************
HRESULT Draw(RECT rcBounds, RECT rcUpdate, LONG lDrawFlags, HDC hdc,
LPVOID pvDrawObject)
{
CDC dc;
dc.Attach(hdc);
dc.Draw3dRect(&rcBounds, RGB(255,0,0), RGB(255,0,0));
dc.Detach();

return S_OK;
}

HRESULT GetPainterInfo(HTML_PAINTER_INFO *pInfo)
{
pInfo->lFlags = HTMLPAINTER_OPAQUE | HTMLPAINTER_HITTEST;
pInfo->lZOrder = HTMLPAINT_ZORDER_ABOVE_CONTENT;

memset(&pInfo->iidDrawObject, 0, sizeof(IID));

pInfo->rcExpand.left = 1;
pInfo->rcExpand.right = 1;
pInfo->rcExpand.top = 1;
pInfo->rcExpand.bottom = 1;

return S_OK;
}
}

.