树形控件可以用于树形的结构，其中有一个根接点(Root)然后下面有许多子结点，而每个子结点上有允许有一个或多个或没有子结点。MFC中使用CTreeCtrl类来封装树形控件的各种操作。-Tree control can be used for tree structure, which has a root contacts (Root) and the following, many sub-nodes, and each child node has allowed one or more o