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) {
		world_map4_01_north_america_over = newImage("images/world-map4_01-north_america.jpg");
		world_map4_02_africa_over = newImage("images/world-map4_02-africa_over.jpg");
		world_map4_04_south_america_over = newImage("images/world-map4_04-south_america.jpg");
		world_map4_05_africa_over = newImage("images/world-map4_05-africa_over.jpg");
		world_map4_06_asia_pacific_over = newImage("images/world-map4_06-asia_pacific_.jpg");
		preloadFlag = true;
	}
}