public static IEnumerable <object> selectObjects
            (string caption,
            IEnumerable <object> elementList)
        {
            SelectObjectForm form = new SelectObjectForm();

            form.Text        = caption;
            form.Elements    = elementList;
            form.MultiSelect = true;
            DialogResult res = form.ShowDialog();

            if (res != DialogResult.OK)
            {
                return(null);
            }
            return(form.Elements);
        }
        public static object selectObject
            (string caption,
            IEnumerable <object> elementList)
        {
            SelectObjectForm form = new SelectObjectForm();

            form.Text        = caption;
            form.Elements    = elementList;
            form.MultiSelect = false;
            DialogResult res = form.ShowDialog();

            if (res != DialogResult.OK)
            {
                return(null);
            }
            return(form.Elements.FirstOrDefault());
        }