How do I add scroll bars for when images exceed a set width or height?

[donJulio]

I've noticed on one site where they use screenshots (1024x768) to show their portfolio and they use PhotoPost. However, when you click on the thumbnail to look at the image, there are scroll bars on the bottom and right, in order to see the image, since it won't fit in the space provided. How can I enable that feature in my installation? For example, if I want the set width at which a scroll bar appears on the bottom to be 720 pixels, where would I do that in the control panel?

Thanks!