http://www.cnblogs.com/duhongyu216/articles/1702591.html
http://www.cnblogs.com/Handll/archive/2009/07/27/1531946.html
https://msdn.microsoft.com/zh-cn/library/system.windows.forms.treeview.aspx
http://www.cnblogs.com/Fskjb/archive/2009/07/08/1519483.html
原文：http://www.cnblogs.com/aoun/p/4260819.html