.NET的TREEVIEW节点若有CHECKBOX, 其只有两种状态, CHECK 或 UNCHECK. 该改良TREEVIEW的节点可带三种状态, CHECK,UNCHECK及未定状态-. NET TreeView node if the CHECKBOX, its only two states, CHECK or UNCHECK. The TreeView nodes can be modified with three states, CHECK, UNCHECK and undeter