Code

ContainerNode c = form.Factory.CreateContainerNode(100, 100, 100, 100);
           c.Bounds = new Rect(e.MousePosition, new Size(75, 75));
           var node = new DiagramNodeAdapter(form, c);
           node.SizeSyncMode = SizeSyncMode.SetSize;
           c.IsManipulationEnabled = true;
           c.Shape =  ContainerShape.RoundedRectangle;
 

Code

   void SetZdown(DiagramItem item)
        {
            //item.ZBottom();

            var parent = ContainerNode.GetContainer(item as DiagramNode);
            item.ZIndex = parent == null ? 0 : parent.ZIndex + 1;

            var ctr = item as ContainerNode;
            if (ctr != null && ctr.SubordinateGroup != null)
            {
                foreach (DiagramNode child in ctr.SubordinateGroup.AttachedNodes)
                    child.ZLevelUp();
            }
        }

        void SetZup(DiagramItem item)
        {


            item.ZTop();
            var ctr = item as ContainerNode;
            if (ctr != null && ctr.SubordinateGroup != null)
            {
                foreach (DiagramNode child in ctr.SubordinateGroup.AttachedNodes)
                    child.ZTop();
            }
        }