Detect when expand pressed on Tree

When using the Tree component I have an item in the tree but I do not have to pre-populate all of the child nodes until the “expand” symbol is pressed. Is it possible to detect when the “expand” of an item is pressed so that I can dynamically load and display the children for that node?

You can use a Tree.ExpandListener, as is done in
this example

Mentioned in
#140: How do I make a lazy Tree or TreeTable?
(requires subscription).

thanks that worked!