Re-arrange nodes on expandcollapse

I am evaluating the GoXam control for Silverlight 4. The version I am using is v2.0.50727

I was wondering if it is possible to re-arrange nodes when a sub tree is collapsed. If so, where could I find out how to do this?
I have a tree layout of related items spanning out horizontally. However, there is not a single root element. There are multiple. Let's say 4. Each one has a variable number of children and so on. On initial load, everything is expanded. This is fine. When I collapse one, I'd like the nodes to re-arrange with the new available space. i.e. if the node that was collapsed was on the bottom, it would move up to be adjacent to the node above it (at the same tree depth) if there's room. Is this possible?
Alternatively, I move the node manually as above, but when I expand the node again, it's position remains the same and does not move back to it's position on first load. Is there a way to force a re-layout of the nodes?

If you include VisibleChanged in the conditions under which a layout is re-performed, I think you’ll get the first behavior automatically. Several samples do this:

<go:TreeLayout ConditionFlags="Standard VisibleChanged" />

I don’t understand how your two requirements are supposed to work together. Is it the case that once the user has moved a node, the expansion or collapse of that node should not move that node?

Try the Incremental Tree sample. Does this give you the behavior that you are looking for? It has also customized the Diagram.DraggingTool, setting its DraggingTool.Inclusions property to “SubTree”.

Of course you could try substituting TreeLayout for the ForceDirectedLayout that the Incremental Tree sample uses, if that’s what you are looking for.

That was exactly what I wanted.

The two requirements were not supposed to work together, it was more an alternative that could possibly be acceptable. However the ConditionFlags setting solved my problem.