private void CollapseAll_DG(NodeViewItem nodeViewItem)
 {
     foreach (NodeViewItem one in nodeViewItem.NodeViewItems)
     {
         one.SetIsExpand(false);
         this.CollapseAll_DG(one);
     }
     nodeViewItem.SetIsExpand(false);
 }
 private void ExpandAll_DG(NodeViewItem nodeViewItem)
 {
     foreach (NodeViewItem one in nodeViewItem.NodeViewItems)
     {
         one.SetIsExpand(true);
         this.ExpandAll_DG(one);
     }
     nodeViewItem.SetIsExpand(true);
 }