AJAX is cool and all, but in this particular case, staying on the same index.htm page and retrieving documents into the body of it was causing navigation problems; state would be lost if you navigated away to another site. I've now reworked the site so that when you call up a document, you get a hard distinct link to that document (using URL parameters), so that you can navigate away and then come back using the browser's Back button. This required ensuring that the find and kwId parameters used for searching were also preserved across pages, so that the retrieved subset of images is retained as you move from image to image.