function newImage(arg) {
		if (document.images) {
			rslt = new Image();
			rslt.src = arg;
			return rslt;
		}
	}

	function changeImages() {
		if (document.images && (preloadFlag == true)) {
			for (var i=0; i<changeImages.arguments.length; i+=2) {
				document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
			}
		}
	}

	var preloadFlag = false;
	function preloadImages() {
		if (document.images) {
			home_over = newImage("/img/topmenu/home-over.jpg");
			mypage_over = newImage("/img/topmenu/mypage-over.jpg");
			trips_over = newImage("/img/topmenu/trips-over.jpg");
			groups_over = newImage("/img/topmenu/groups-over.jpg");
			users_over = newImage("/img/topmenu/users-over.jpg");
			about_over = newImage("/img/topmenu/about-over.jpg");
			img_tab = newImage("img/tab.png");
			preloadFlag = true;
		}
	}