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) {
		classroom_nav_over = newImage("images/classroom-nav-over.gif");
		building_wide_nav_over = newImage("images/building-wide-nav-over.gif");
		campus_wide_nav_over = newImage("images/campus-wide-nav-over.gif");
		performance_btn_over = newImage("images/performance-btn-over.gif");
		daylight_harvesting_btn_over = newImage("images/daylight-harvesting-btn-ove.gif");
		simplify_btn_over = newImage("images/simplify-btn-over.gif");
		investment_btn_over = newImage("images/investment-btn-over.gif");
		preloadFlag = true;
	}
}