tree.addCloseHandler( new CloseHandler<TreeItem>() {
public void onClose(CloseEvent<TreeItem> event) {
swapTitleWithUserObject( event.getTarget() );
}
} );
tree.addOpenHandler( new OpenHandler<TreeItem>() {
public void onOpen(OpenEvent<TreeItem> event) {
swapTitleWithUserObject( event.getTarget() );
}
} );
layout.addRow( tree );