RealTimeDragSelectingTool again

I’ve written a RealTimeDragSelectingTool like in the Possible bug in dragselectiontool thread.

Now I realized that the part which unselect previously selected Parts is working, but doesn’t reflect in the diagram. The Parts are still drawing with the resize-adorner. I’m sure this was working in 2.1.
Is it possible there is a bug?

            // select parts, and unselect all other previously selected parts
            // this tries to avoid deselecting and then reselecting any Part
            List<Part> tounselect = new List<Part>();
            foreach (Part p in diagram.SelectedParts)
                if (!parts.Contains(p)) tounselect.Add(p);
            foreach (Part p in tounselect)
                p.IsSelected = false;  // <--- is modifing SelectedParts, but not the Adorner
            foreach (Part p in parts)
                if (!p.IsSelected) p.IsSelected = true;

Sorry, my fault.
I found a bug in my code - I reset the selected nodes.