treeview - wrapper:每个条目都要中断，而不是完整的根

I need to have a Treeview in WPF (C#) with Vertical Wrapping for all TreeView-Items. So far, I got it to work for root items: When the control gets smaller in height, they and all of their childs get broken. But I want a behaviour that the child TreeView-Items get broken too. Please look at those examples as it's not easy to explain in words:I need to have a Treeview in WPF (C#) with Vert