public override void SetModifiedFlag(bool isModified)
        {
            base.SetModifiedFlag(isModified);

            if (isModified)
            {
                DesignSurface.AddToJournal();
            }
        }
        public override void Load(XElement root)
        {
            Assert.ArgumentNotNull(root, nameof(root));

            DesignSurface.Clear();

            LoadState(root);

            SetModifiedFlag(false);
            DesignSurface.ClearJournal();
            DesignSurface.AddToJournal();
        }