//plugin to get height of hidden element
(function($) {
	$.fn.sandbox = function(fn) {
		var element = $(this).clone(), result;
		// make the element take space in the page but invisible
		element.css({visibility: 'hidden', display: 'block'}).insertAfter(this);
		// to override any display: none !important you may have been using
		element.attr('style', element.attr('style').replace('block', 'block !important'));
		result = fn.apply(element);
		element.remove();
		return result;
	};
})(jQuery);