Disabling option + node click and move

On my Mac, when I press the option button, and then click on a node and move it around, it copies the node. How can I stop this behaviour?

I tried using the CommandHandler as follows, but it didn’t work:

diagram.commandHandler.doKeyDown = function() {
                return false;

You can set Diagram.allowCopy to false, or more specifically for dragging you can set DraggingTool.isCopyEnabled to false.

So when initializing a Diagram using go.GraphObject.make:

  $(go.Diagram, . . .,
      "draggingTool.isCopyEnabled": false,
      . . .

Read more about the choices at GoJS User Permissions -- Northwoods Software