To complement what Helmut says I suspect this has to do with menus in XaAESbeing windows, so that when you move from one menu to another you actually areopening/closing windows. And when the AES closes a window it sends a redrawmessage. I'm counting on Helmut to correct me if I'm wrong :-)
I can't believe that, because that would mean it may send an redraw to an area which will be occupied by the newly opened menu item.