This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
It's unclear which version of Struts you're using. Struts 2 has a Dojo-based tree control (although as of S2.1.6 we've deprecated the Dojo-based Ajax tags). There are about a million other tree components out there, but none are part of Struts itself.
subject: dynamic tree menu using struts tiles framework