private void RefreshFiltering(RasteredItemsControl ctl)
        {

        }
        private void RefreshFiltering(RasteredItemsControl ctl)
        {
            ctl.Items.Filter = obj =>
            {
                var tObj = obj as IEvent;
                if (!IsGroupFilterActive) return true;

                var tBaseEvents = from evt in PlanFile.Instance.KnownBaseEvents
                                  where evt.BasicCode == tObj.BasicCode && (evt.Groups.Count() <= 1 || evt.Group == GroupID.Empty || evt.Group == tObj.Group || (!tObj.Group.IsSingleGroup && tObj.Group.Value.Split('+').Contains(evt.Group.Value)))
                                  select evt;

                return (tBaseEvents.Count() > 0);
            };
        }