Ctrl+Drag making a copy of GoObject

In both Demo1 and ProtoApp samples, Ctrl+Dragging will make a copy of selected object, how do I disable feature?

GoView.AllowCopy = false


That disables Copy completely. I only wanna disable copying using Control+Dragging without Allowing regular copying.

public class NoCopyDraggingTool : GoToolDragging {
public NoCopyDraggingTool(GoView v) : base(v) { }
public override bool MayBeCopying() {
return false;
public override bool MustBeCopying() {
return false;
Install by replacing the standard dragging tool:
goView1.ReplaceMouseTool(typeof(GoToolDragging), new NoCopyDraggingTool(goView1));