protected override void OnDestroy()
        {
            if (disableUpdateRestoreTime != 0)
            {
                Script.DisableUpdate     = false;
                disableUpdateRestoreTime = 0;

                //to refresh preview texture
                if (!RenderingSystem.Disposed)
                {
                    Script.RaiseCodeChangedEventAndSetNeedUpdate();
                }
            }

            base.OnDestroy();
        }