var preloadFlag = false;
function clearDefault(el) {
	if (el.defaultValue==el.value) el.value = "";
}
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];
		}
	}
}
function preloadImages() {
	if (document.images) {
		nav_about_over = newImage("/images/nav_about-over.gif");
		nav_trad_over = newImage("/images/nav_trad-over.gif");
		nav_alt_over = newImage("/images/nav_alt-over.gif");
		nav_research_over = newImage("/images/nav_research-over.gif");
		nav_for_over = newImage("/images/nav_for-over.gif");
		preloadFlag = true;
	}
}