This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
In Struts 1.2.9 and above, you must specify callellable="true" in your action mapping in the struts-config.xml file if you want to use the cancel function. However, since you're using Struts 1.2.7, this doesn't apply to you.