final FastTree cancelEventTree = new FastTree();
FastTreeItem firstBranch = cancelEventTree.addItem("Select Me!");
firstBranch.addItem("No! Select Me!");
firstBranch.addItem("No! Select Me!");
firstBranch.addItem("No! Select Me!");
FastTreeItem secondBranch = cancelEventTree.addItem("Don't Select me!");
secondBranch.addItem("Not me!");
secondBranch.addItem("Not me!");
secondBranch.addItem("Not me!");
cancelEventTree.addBeforeSelectionHandler(new BeforeSelectionHandler<FastTreeItem>() {