How to pretend from the document modifyin

When I moved mouse on a object, I increased its size as following:
public override bool OnMouseOver(GoInputEventArgs evt, GoView view)
if (view != null && !(view is GoPalette))
foreach (GoPort p in this.Ports)

 p.Document.SkipsUndoManager = true;
                p.Size = new SizeF(5, 5);
                p.Style = GoPortStyle.Ellipse;
                p.Brush = null;
 p.Document.SkipsUndoManager = false;
        return false;

But When the mouse moved out, the Modified field of the its document was true.
There’s no MouseMoveOuter event. Tell me How to pretend from the document modifying in the case.

The FlowCharter sample uses a GoView.BackgroundHover event to decide to make invisible all the ports that were made visible in GoObject.OnMouseOver methods. Or you can override GoView.DoBackgroundMouseOver.

It’s alright