Berzohr

do you mean in pro version?

Found!
In filterMediank-lbox-js.js remove code from numbers 1226 to 1238.

This is the code to delete:

if ($.fn.mousewheel) {
			wrap.bind('mousewheel.fb', function(e, delta) {
				if (busy) {
					e.preventDefault();

				} else if ($(e.target).get(0).clientHeight == 0 || $(e.target).get(0).scrollHeight === $(e.target).get(0).clientHeight) {
					e.preventDefault();
					$.fancybox[ delta > 0 ? 'prev' : 'next']();
				}
			});
		}