Code

		foreach (DiagramNode node in Diagram.Nodes)
		{
		    if (node.Bounds.Contains(point))
		    {
			  var anchorPoints = node.AnchorPattern.Points;
			  int nAnhcorIdx = 0;
			  foreach (AnchorPoint pnt in anchorPoints)
			  {
				Point nodePnt = node.TransformDiagramToItem(point);
				double dbX = pnt.X / 100 * node.Bounds.Width;
				double dbY = pnt.Y / 100 * node.Bounds.Height;
				Point anchorPnt = new Point(dbX, dbY);
				if (Utilities.Distance(nodePnt, anchorPnt) < 8)
				{
				    foreach (DiagramLink lnk in node.GetAllLinks())
				    {
					  if ((lnk.Destination == node &&
						lnk.DestinationAnchor == nAnhcorIdx) ||
						(lnk.Origin == node && lnk.OriginAnchor == nAnhcorIdx))
					  {
						return new InteractionState(null, -1, Action.None);
					  }
				    }
				}
				nAnhcorIdx++;
			  }
			  return base.StartDraw(point);
		    }
 

Code

private void AlignAnchorsToGrid(DiagramNode a_Node)
{
    var anchorPnts = a_Node.AnchorPattern.Points;
    foreach (AnchorPoint point in anchorPnts)
    {
	  double dblX = a_Node.Bounds.TopLeft.X + a_Node.Bounds.Width * (point.X / 100);
	  double dblY = a_Node.Bounds.TopLeft.Y + a_Node.Bounds.Height * (point.Y / 100); ;
	  Point diagramPoint = new Point(dblX, dblY);
	  Point alignedPnt = m_Diagram.AlignPointToGrid(diagramPoint);
	  Point nodePoint = a_Node.TransformDiagramToItem(alignedPnt);
	  point.X = nodePoint.X / a_Node.Bounds.Width * 100.0;
	  point.Y = nodePoint.Y / a_Node.Bounds.Height * 100.0;
	  foreach (DiagramLink link in a_Node.GetAllLinks())
	  {
		for (int i = 0; i < link.ControlPoints.Count; ++i)
		{
		    if (link.ControlPoints[i].Equals(diagramPoint))
			  link.ControlPoints[i] = m_Diagram.AlignPointToGrid(diagramPoint);
		    else
			  link.ControlPoints[i] = m_Diagram.AlignPointToGrid(link.ControlPoints[i]);
		}
		link.UpdateFromPoints(false, true);
	  }
    }
}