I tried that with the latest source but the nodes are properly positioned on expanding/collapsing either by code or by hand. I'd suggest you give the official release a try as soon as we announce it. It should be ready and uploaded tomorrow.
You can also send us a sample which shows the problem via a support ticket
(attachments are not allowed in the forums). This way we can test the exact scenario on our end and make sure the problem does not appear anymore.
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