if you click in a picture to enlarge it, it would be great if this zoomed picture would be shown in full screen...
Heard back from the Floatbox developer, and as I suspected, that functionality isn't part of the script, and never will be. In short, it will never "break out" of the frame, and it will never make the frame larger than the viewport.
I don't have the Javascript skills to hack into the script and make that happen.