树遍历没有递归/堆栈使用（C＃）？

I'm working with WPF and I'm developing a complex usercontrol, which is composed of a tree with rich functionality etc. For this purpose I used a View-Model design pattern, because some operations couldn't be achieved directly in WPF. So I take the IHierarchyItem (which is a node and pass it to this constructor to create a tree structure)I'm working with WPF and I'm developing a compl