oky this is working now when drag node already on canvas, but how to revoke the action in following scenarios

Scenario 1

I have NodeList on right panel, select an item from it and drag and drop on canvas, how to avoid if dropping node overlap with existing item



I tried following but it contains compile time errors

        private void OnNodeCreated(object sender, NodeEventArgs e)
        {

            if (IsMovingNodeOverlap(e.Node, 2))
            {
                e.Cancel = true;
            }
            else
            {
                e.Cancel = false;
            }
        }
        public bool IsMovingNodeOverlap(DiagramNode modifiedNode, double minDist)
        {
            bool isCurrentNodeOverlap = false;

            var queue = new Queue<DiagramNode>();
            queue.Enqueue(modifiedNode);

            while (queue.Count > 0)
            {
                var node = queue.Dequeue();
                var nodeCenter = node.GetCenter();
                var overlaps = FindOverlaps(node, minDist);

                if (overlaps.Count > 0)
                {
                    isCurrentNodeOverlap = true;
                }
                else
                {
                    isCurrentNodeOverlap = false;
                }

            }

            return isCurrentNodeOverlap;
        } 

Scenario 2

Existing Node can rotate to overlap with another existing node