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) {
		nav_church_over = newImage("images/nav_church-over.jpg");
		nav_ct_over = newImage("images/nav_ct-over.jpg");
		nav_lte_over = newImage("images/nav_lte-over.jpg");
		nav_har_over = newImage("images/nav_har-over.jpg");
		nav_ujima_over = newImage("images/nav_ujima-over.jpg");
		preloadFlag = true;
	}
}