第二个问题 nCode只是让你选择用哪种方式。 A flag indicating the type of action to be taken. This flag can have one of the following values:
TVE_COLLAPSE Collapses the list.
TVE_COLLAPSERESET Collapses the list and removes the child items. The TVIS_EXPANDEDONCE state flag is reset. This flag must be used with the TVE_COLLAPSE flag.
TVE_EXPAND Expands the list.
TVE_TOGGLE Collapses the list if it is currently expanded or expands it if it is currently collapsed.