Major Description
The expansion of the tree nodes on the Netui tree control is handled by
overriding the onExpand method of the TreeElement class. This method is
responsible for building out the children nodes. The onExpand method takes
only the request as a parameter. However, when building out nodes and adding
enhanced UI functionality, there are cases that need to have access to both
the request and response. For example, both are needed to rewrite action
urls using the PageFlowUtils utility class.