Graph spacing

I use custom node size and the graph looks too dense. I tried to make more space between the nodes by setting the node separation and layer separation but they both do not seems to make any effect.

       Microsoft.Msagl.Drawing.Graph graph = new Microsoft.Msagl.Drawing.Graph("");
        graph.AddEdge("A", "B");
        graph.AddEdge("B", "C");
        graph.AddEdge("C", "D");
        graph.AddEdge("C", "E");
        graph.AddEdge("C", "F");
        graph.AddEdge("C", "G");
        graph.AddEdge("A", "H");
        graph.AddEdge("E", "H");
        graph.AddEdge("F", "H");

        foreach (var node in graph.Nodes)
        {
            int w = 150;
            int h = 80;

            node.NodeBoundaryDelegate = new DelegateToSetNodeBoundary(p => CurveFactory.CreateRectangle(w, h, new Microsoft.Msagl.Core.Geometry.Point()));
        }


        graph.Attr.LayerDirection = LayerDirection.LR;
        graph.Attr.NodeSeparation = 200;
        graph.Attr.LayerSeparation = 200;

        Microsoft.Msagl.GraphViewerGdi.GraphRenderer renderer = new Microsoft.Msagl.GraphViewerGdi.GraphRenderer(graph);
        renderer.CalculateLayout();

        int width = 1500;
        Bitmap bitmap = new Bitmap(width, (int)(graph.Height * (width / graph.Width)), PixelFormat.Format32bppPArgb);
        renderer.Render(bitmap);
        bitmap.Save("c:\\temp\\test2.png");

Start with the reproduced C# example, especially GraphRenderer.CalculateLayout and the assignments to NodeSeparation and LayerSeparation. Compare the calculated node positions and graph dimensions with the custom 150x80 node boundaries. The issue is done when those separation settings visibly affect the rendered layout, or their intended behavior is documented.