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_home_over = newImage("images/nav_home-over.gif");
		nav_stress_over = newImage("images/nav_stress-over.gif");
		nav_test_over = newImage("images/nav_test-over.gif");
		nav_serv_over = newImage("images/nav_serv-over.gif");
		nav_events_over = newImage("images/nav_events-over.gif");
		nav_news_over = newImage("images/nav_news-over.gif");
		nav_inter_over = newImage("images/nav_inter-over.gif");
		nav_bio_over = newImage("images/nav_bio-over.gif");
		preloadFlag = true;
	}
}

						
function toggle_dropmenu(id){
	count = 1;
	while (count <= 10){
		var step = id+'_'+count;
		if (document.getElementById(step)){
		document.getElementById(step).style.display = (document.getElementById(step).style.display == 'block') ? 'none' : 'block';
		}
		count++;
	}
}

function roll_dropmenu(id, roll_class){
	document.getElementById(id).className = roll_class;
}