I'm just a user of Juicebox Pro, and not an expert. Although I put my thumbnails below the image in my gallery, having the thumbs above the gallery is possible. On the configuration page ( http://www.juicebox.net/support/config_options/ ), see the thumbnail options: http://www.juicebox.net/support/config_ … il-options . One choice is thumbsPosition=TOP.
However, if the viewer chooses to turn the thumbnail display off or on (assuming you allow this, in a given gallery), the main image will resize, anyway, i.e., regardless of where the thumbs are. (This assumes that the image has room to resize, e.g., it not already taking up all the available width, for instance, of the viewing window.)
Personally, I don't see the image resizing in these circumstances to be an issue -- in fact, I like it. I think that most viewers will tend to leave the thumbs in one state, either visible or not visible. So the images will be in one state. What I like is that if a viewer has the thumbs on, but wants a larger view of one or more images, she or he can simply turn off the thumb display... and the image will enlarge a bit (depending on browser real estate); this is often easier and quicker than using the option to open the full-size image in a new browser window.
Cheers,
Bill P.