Links are assumed to go from the parent node to the children nodes, unless TreePath is set to "Source".

This will expand a tree child node only if its GetWasTreeExpanded was true.

This also calls SetIsTreeExpanded to set that attached property, and if appropriate SetWasTreeExpanded, to support data binding whether the tree is expanded.

This operation is performed within an "Expand Tree" transaction.

Reference

Node Class
Node Members