/// <summary>
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }

            _instance = null;

            base.Dispose(disposing);
        }
        public static SnapshotRule DisplayInstance(SnapshotRule schedule = null)
        {
            _instance = _instance ?? new EditSnapshotRuleForm(schedule);

            _instance.ShowDialog();

            SnapshotRule ret = _instance.DialogResult == DialogResult.Yes
        ? _instance.SnapshotRule
        : null;

            _instance = null;

            return(ret);
        }