treeview 中节点伸展和收缩问题？
treeview 中节点伸展或收缩后，节点的图像如何随着改变？
Set nodX = TreeView1.Nodes.Add(, , "root1", "水准测量", "pic1", "pic2")
Set nodX = TreeView1.Nodes.Add("root1", tvwChild, "root1_1", "闭合水准路线", "pic1", "pic2")
Set nodX = TreeView1.Nodes.Add("root1", tvwChild, "root1_2", "附合水准路线", "pic1", "pic2")
Set nodX = TreeView1.Nodes.Add("root1", tvwChild, "root1_3", "支水准路线", "pic1", "pic2")
Set nodX = TreeView1.Nodes.Add("root1", tvwChild, "root1_4", "水准网（严密）", "pic1", "pic2")
nodX.Image = "pic1"
nodX.ExpandedImage = "pic2"
还是不行，两个pic1和pic2不能来回切换，为什么？