I am not really sure what your trying to convey. The show photo screen is going to be whatever width it is going to be to convey that information. Just like a sausage that your stuffing do not overstuff.
What I mean is if your constricting the page to show in 800pixels but there is 1000pixels wide you will see scrollbars. You can not conpare the showphoto to the index. 7.1 was exactly the same as 8.0 I have seen people post about how to keep showphoto into there page designs from all versions.
I can only assume this is what your talking about so take that smaller browser same principle as you restricting a site in a table size. If that 17 inch monitor has a max resolution of 800 pixels wide and your trying to show 1000 pixels you will see a scrollbar.
Not much we can do about that other than say be mindful maybe have smaller mediums.