private void OnActionPointJointsUpdated(object sender, RobotJointsEventArgs args)
 {
     try {
         ActionButton btn = GetButton(args.Data.Id, JointsDynamicList);
         btn.GetComponentInParent <ServiceButton>().State = args.Data.IsValid;
     } catch (ItemNotFoundException) {
         // not currently opened action point
     }
 }