CTreeView 中在OnLButtonDown函数如何判断鼠标是否点击到节点

CTreeView 中在OnLButtonDown函数怎么判断鼠标是否点击到节点？
如题，就是区分单击在TREE上和TREE外的情况，

目前我发现OnLButtonDown，OnClick两个函数两种情况都会响应

------解决方案--------------------
http://msdn2.microsoft.com/en-us/library/x0w7ft34(VS.80).aspx
------解决方案--------------------
CPoint point;
GetCursorPos(& point);
CTreeCtrl * pTreeCtrl=NULL;
pTreeCtrl = ( (CTreeCtrl *)GetDlgItem(IDC_TREE_SHAREVIEW) );
if(pTreeCtrl == NULL)
{
return;
}
pTreeCtrl-> ScreenToClient(&point);

UINT nFlags;
HTREEITEM hItem;
hItem = pTreeCtrl-> HitTest(point,&nFlags);