Make javascript popup images scrollable?

[dynamica]

I've got a lot of product images that are larger that most people's resolutions (some are much bigger than 1024 X 768) and when you click 'see larger image,' the popup window is the size of the screen, but the image is bigger than the window so you loose a lot of the image. You can see an example of what I mean here:

http://doctorsmedicalsupplies.com/ca...&products_id=4

Is there any way to make the javascript popup window scrollable? I think the change would probably have to be made to this file: includes/modules/pages/popup_image/jscript_main.php, but I don't know what to change. Anyone know how to fix this?