请教TREEVIEW的TVN_SELCHANGED与NM_CLICK的消息参数的问题？？？

[wesleyluo]

treeview的这两个消息参数都是(NMHDR * pNotifyStruct, LRESULT * result)这样。
但是为什么在TVN_SELCHANGED消息里面，可以直接把NMHDR参数转换成LPNMTREEVIEW，
然后直接通过LPNMTREEVIEW结构获取到HTREEITEM，即LPNMTREEVIEW.itemNew.hItem;

但是在响应NM_CLICK消息时，要获取到Item却要通过HitTest()来获取呢？

是他们响应时传递的参数不一样吗？
如果不一样，那分别是怎么样的参数呢？

[schlafenhamster]

在TVN_SELCHANGED消息（N）里面,控件已经把参数填好了。
通常不必用NM_CLICK消息，这是叫控件做，所以要hittest

[Eleven]

TVN_SELCHANGED Notification
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Notifies a tree-view control's parent window that the selection has changed from one item to another. This notification message is sent in the form of a WM_NOTIFY message.


NM_CLICK (tree view) Notification
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Notifies the parent window of a tree-view control that the user has clicked the left mouse button within the control. This notification is sent in the form of a WM_NOTIFY message.