public void AddFilter(String propertyName, Control control, List <Object> rangeOfValues = null) { if (_filters.ContainsKey(propertyName)) { _filters[propertyName].AddControl(control, rangeOfValues); } else { var f = new Filter(propertyName); f.CLV = this; f.AddControl(control, rangeOfValues); _filters[propertyName] = f; } }