I think you need a combination of the GetChild() and GetNextSibling() methods. I’m not sure that MS would (or even should) publish internal structures like that, but a good place to start is:
[mailto:email@example.com] On Behalf Of Igor Anufriyenko
Sent: Tuesday, 10 January, 2006 00:48
Subject: [perl-win32-gui-users] TreeView Node structure
Is it possible to get a list of TreeView Node children (items) or their handles?
ItemInfo and GetItem methods return just a value of 0 or 1 for the -children key.
Is their a document describing Node object data structure ?