Code

void DistributeLinks(DiagramNode node)
{
	var allLinks = node.GetAllLinks();

	var leftLinks = (from DiagramLink link in allLinks
		where (Math.Abs(node.Bounds.Left - AdjacentPoint(node, link).X) < 0.1)
		select link).ToList();
	leftLinks.Sort(new LinkComparer(node, false));
	DistributeVertically(leftLinks, node, node.Bounds.Left);

	var topLinks = (from DiagramLink link in allLinks
		where (Math.Abs(node.Bounds.Top - AdjacentPoint(node, link).Y) < 0.1)
		select link).ToList();
	topLinks.Sort(new LinkComparer(node, true));
	DistributeHorizontally(topLinks, node, node.Bounds.Top);

	var rightLinks = (from DiagramLink link in allLinks
		where (Math.Abs(node.Bounds.Right - AdjacentPoint(node, link).X) < 0.1)
		select link).ToList();
	rightLinks.Sort(new LinkComparer(node, false));
	DistributeVertically(rightLinks, node, node.Bounds.Right);

	var bottomLinks = (from DiagramLink link in allLinks
		where (Math.Abs(node.Bounds.Bottom - AdjacentPoint(node, link).Y) < 0.1)
		select link).ToList();
	bottomLinks.Sort(new LinkComparer(node, true));
	DistributeHorizontally(bottomLinks, node, node.Bounds.Bottom);
}

private void DistributeHorizontally(IList<DiagramLink> links, DiagramNode node, float y)
{
	float d = node.Bounds.Width / (links.Count + 1);
	float x = node.Bounds.Left + d;
	foreach (DiagramLink link in links)
	{
		int index = link.Origin == node ? 0 : link.ControlPoints.Count - 1;
		PointF c = node.GetCenter();
		float h = node.Bounds.Height;
		PointF p1 = new PointF(x, y + (c.Y > y ? - h: +h));
		PointF p2 = new PointF(x, c.Y);
		PointF p = node.GetIntersection(p1, p2);
		link.ControlPoints[index] = p;
		link.UpdateFromPoints(true, false);
		x += d;
	}
}

private void DistributeVertically(IList<DiagramLink> links, DiagramNode node, float x)
{
	float d = node.Bounds.Height / (links.Count + 1);
	float y = node.Bounds.Top + d;
	foreach (DiagramLink link in links)
	{
		int index = link.Origin == node ? 0 : link.ControlPoints.Count - 1;
		PointF c = node.GetCenter();
		float w = node.Bounds.Width;
		PointF p1 = new PointF(x + (c.X > x ? -w : +w), y);
		PointF p2 = new PointF(c.X, y);
		PointF p = node.GetIntersection(p1, p2);
		link.ControlPoints[index] = p;
		link.UpdateFromPoints(true, false);
		y += d;
	}
}

static PointF FarPoint(DiagramNode node, DiagramLink link)
{
	if (node == link.Destination)
		return link.ControlPoints[0];
	else
		return link.ControlPoints[link.ControlPoints.Count - 1];
}

static PointF AdjacentPoint(DiagramNode node, DiagramLink link)
{
	if (node == link.Origin)
		return link.ControlPoints[0];
	else
		return link.ControlPoints[link.ControlPoints.Count - 1];
}

public class LinkComparer : IComparer<DiagramLink>
{
	public LinkComparer(DiagramNode node, bool byX)
	{
		this.node = node;
		this.byX = byX;
	}

	public int Compare(DiagramLink link1, DiagramLink link2)
	{
		var a1 = byX ? AdjacentPoint(node, link1).X : AdjacentPoint(node, link1).Y;
		var a2 = byX ? AdjacentPoint(node, link2).X : AdjacentPoint(node, link2).Y;
		var f1 = byX ? FarPoint(node, link1).X : FarPoint(node, link1).Y;
		var f2 = byX ? FarPoint(node, link2).X : FarPoint(node, link2).Y;

		int result = a1.CompareTo(a2);
		if (result == 0)
			result = f1.CompareTo(f2);
		return result;
	}

	private DiagramNode node;
	private bool byX;
}