I have a large set of shapes. I want to allow the user to cancel the layout if they don't want to wait anymore. Can you please suggest the best way to go about this.

I have been using the NOrthogonalGraphLayout as follows:

NOrthogonalGraphLayout layout = new NOrthogonalGraphLayout();
layout.MultiThreaded = true;
NNodeList shapes = document.ActiveLayer.Children(NFilters.Shape2D);
NLayoutContext layoutContext = new NLayoutContext();
layoutContext.GraphAdapter = new NShapeGraphAdapter();
layoutContext.BodyAdapter = new NShapeBodyAdapter(document);

NDrawingBodyContainerAdapter adapter = new NDrawingBodyContainerAdapter(document);
layoutContext.BodyContainerAdapter = adapter;
layout.Layout(shapes, layoutContext);

I have tried subscribing to the LayingOutGraph event, so that I could set the cancel argument, but it only seems to fire once.
I also tried calling the layout routine in another thread, however that had a cross-thread problem accessing the view.

Also, is there a way to show a progress UI during the layout?

Thanks.