Code

var leftStacks = CreateTestStacks(2, 4, 1, 1);
var rightStacks = CreateTestStacks(4, 1, 0, 6);

double padding = 10, stackStart = 20, stacksPadding = 40;
for (int i = 0; i < 4; i++)
{
	double yl = stackStart;
	foreach (var node in leftStacks[i])
	{
		node.Move(20, yl);
		yl += node.Bounds.Height + padding;
	}

	double yr = stackStart;
	foreach (var node in rightStacks[i])
	{
		node.Move(80, yr);
		yr += node.Bounds.Height + padding;
	}

	stackStart = Math.Max(yl, yr) + stacksPadding;
}

List<List<DiagramNode>> CreateTestStacks(params int[] stackSizes)
{
	var stacks = new List<List<DiagramNode>>();
	foreach (int size in stackSizes)
	{
		var stack = new List<DiagramNode>();
		for (int i = 0; i < size; i++)
			stack.Add(diagram.Factory.CreateShapeNode(defBounds));
		stacks.Add(stack);
	}
	return stacks;
}

Rect defBounds = new Rect(0, 0, 30, 30);