我的代码下：TreeCtrl上添加一个响应消息，TVN_ITEMEXPANDED的消息。 添加后的函数中系统自动添加这样一个语句： NM_TREEVIEW* pNMTreeView = (NM_TREEVIEW*)pNMHDR 当展开或者收起时会激发这个函数，其中结构指针pNMTreeView的action参数，就记录了是打开还是关闭，即 -My code under: TreeCtrl add a response message, TVN_ITEMEXPANDED news. After adding function automatically add such a statement: NM_TREEVIEW* pNMTreeView = (NM_TREEVIEW*) pNMHDR　when expanded or retracted will stimulate this function, in which the action parameter structure pointer pNMTreeView, on the record is open or closed, that