private El getGroup(String groupName) {
El g = el().selectNode("#" + getId() + "-" + groupName);
if (g == null) {
g = new El(DOM.createDiv());
g.makePositionable(true);
g.dom.setAttribute("role", "group");
g.addStyleName(HideMode.OFFSETS.value());
g.addStyleName("x-menu-radio-group");
g.setId(getId() + "-" + groupName);
el().appendChild(g.dom);