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

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

function changeImages() {
	changeImagesArray(changeImages.arguments);
}

function toggleImages() {
	for (var i=0; i<toggleImages.arguments.length; i+=2) {
		if (selected == toggleImages.arguments[i])      changeImagesArray(toggleImages.arguments[i+1]);
	}
}

	
var preloadFlag = false;
function preloadImages() {
	if (document.images) {
		id1_over = newImage('../images/menu_13on.jpg');
		id1_sel = newImage('../images/menu_13on.jpg');
		id2_sel = newImage('../images/menu_15on.jpg');
		id2_over = newImage('../images/menu_15on.jpg');
		id3_sel = newImage('../images/menu_17on.jpg');
		id3_over = newImage('../images/menu_17on.jpg');
		id4_sel = newImage('../images/menu_19on.jpg');
		id4_over = newImage('../images/menu_19on.jpg');
		
		preloadFlag = true;
	}
}