Code

private void miLayoutContainers_Click(object sender, EventArgs e)
{
	LayeredLayout layeredLayout = new LayeredLayout();
	layeredLayout.Orientation = MindFusion.Diagramming.Layout.Orientation.Horizontal;
	layeredLayout.StraightenLongLinks = true;

	TopologicalLayout topologicalLayout = new TopologicalLayout();
	topologicalLayout.SplitGraph = true;
	topologicalLayout.Orientation = MindFusion.Diagramming.Layout.Orientation.Vertical;

	Arrange(diagram, topologicalLayout, layeredLayout);
}

private DiagramItemCollection GetContainerItems(ContainerNode container)
{
	DiagramItemCollection items = new DiagramItemCollection();
	foreach (DiagramNode node in container.SubordinateGroup.AttachedNodes)
	{
		items.Add(node);
		foreach (DiagramLink link in node.GetAllLinks())
		{
			DiagramNode node2 = GetOtherEnd(link, node);
			if (ContainerNode.GetContainer(node2) == container && !items.Contains(link))
				items.Add(link);
		}
	}
	return items;
}

private DiagramNode GetOtherEnd(DiagramLink link, DiagramNode node)
{
	if (node == link.Origin)
		return link.Destination;

	if (node == link.Destination)
		return link.Origin;

	return null;
}

private void Arrange(Diagram diagram, Layout outerLayout, Layout innerLayout)
{
	foreach (DiagramNode node in diagram.Nodes)
	{
		ContainerNode container = node as ContainerNode;
		if (container == null)
			continue;

		innerLayout.Arrange(diagram, GetContainerItems(container));
		container.UpdateBounds();
	}

	outerLayout.Arrange(diagram);

	foreach (DiagramLink link in diagram.Links)
	{
		if (ContainerNode.GetContainer(link.Origin) != ContainerNode.GetContainer(link.Destination))
			link.Route();
	}

	diagram.ResizeToFitItems(5);
}