Specific Popups Addon

[opulence]

I'd like to be able to ad code of somesort so that a popup appears after every 5th click on an actual gallery image.

So if someone were just browsing between pages, and the main page, etc - the popup would not occur, and the popup would only occur if a surfer was browsing between actual gallery images on every 5th click.

I believe this would mean adding some sort of popup code to displayimage.php

I'm wondering if anyone could help me by letting me know if that would work (if adding popup code to displayimage.php would make it so that a popup would only occur if someone were to click on an actual gallery image as opposed to just browsing) - and possibly, what code and where to put it?

Thanks,
opulence