//循环删除树的所有根结点
long ll_handle,ll_handleNext
ll_handleNext=0
ll_handle = tv_1.finditem(RootTreeItem! ,0)
do while ll_handle >0
ll_handleNext = tv_1.finditem(NextTreeItem! ,ll_handle) //同级的下一个节点
tv_1.deleteitem( ll_handle)
ll_handle=ll_handleNext
loop