private void DeleteSelectedProperties() { foreach (var uiProperty in propertiesListView.SelectedItems.OfType <UIProperty>().ToList()) { var uiRelatedProperty = uiProperty as UIRelatedProperty; if (uiRelatedProperty != null && RelationsContenerByRelatedProperty.ContainsKey(uiRelatedProperty)) { var relationContener = RelationsContenerByRelatedProperty[uiRelatedProperty]; Designer.Children.Remove(relationContener); relationContener.OnRemove(); } UIType.DeleteProperty(uiProperty); } }