/* caches an image */
function newImage(arg) {
	if (document.images) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}

/* swaps rollover images */
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];
		}
	}
}

/* list of images to preload into cache */
var preloadFlag = false;
function preloadImages() {
	if (document.images) {
		home_on = newImage("images/navbar_home-on.gif");
		planning_on = newImage("images/navbar_planning-on.gif");
		estimating_on = newImage("images/navbar_estimating-on.gif");
		background_on = newImage("images/navbar_background-on.gif");
		contact_on = newImage("images/navbar_contact-on.gif");
		preloadFlag = true;
	}
}