private void CreateCommentRelationship() { CommentShape shape1 = first as CommentShape; CommentShape shape2 = second as CommentShape; if (shape1 != null) { diagram.AddCommentRelationship(shape1.Comment, second.Entity); } else if (shape2 != null) { diagram.AddCommentRelationship(shape2.Comment, first.Entity); } else { MessageBox.Show(Strings.ErrorCannotCreateRelationship); } }