演示在树形结构中，怎样添加新节点并进行编辑。观察节点的展开以及收缩，以及滚动面板怎样让添加的节点保持在视图中。-Demonstration in the tree structure, how to add a new node and edit it. From one node to the start and shrink, and how to add scrolling panel to keep the nodes in the view.