private void geoset_PropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            M2Geoset g = sender as M2Geoset;

            if (e.PropertyName == "Visible")
            {
                M2SceneNode node = ModelSceneService.Instance.MainM2SceneNode;
                if (node != null)
                {
                    node.ShowGeoset(g.Index, g.Visible);
                }
            }
        }