The "TreeExpanderButton", which changes the Node.isTreeExpanded property, really only works with tree structures. When you want to hide/show the "downstream" nodes from a given node, using the "TreeExpanderButton" might not do what you like, especially when there are cycles in the graph structure.
Instead, this sample implements a "Button" with custom behavior to modify the visibility of each Node.
If this behavior is still not quite right for your app, you can adapt the behavior implemented in the
expandFrom functions to use different criteria for when to stop recursion.