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) {
		home_btn_over = newImage("images/home_btn-over.gif");
		conf_btn_over = newImage("images/conf_btn-over.gif");
		agenda_btn_over = newImage("images/agenda_btn-over.gif");
		speakers_btn_over = newImage("images/speakers_btn-over.gif");
		spon_btn_over = newImage("images/spon_btn-over.gif");
		why_btn_over = newImage("images/why_btn-over.gif");
		app_btn_over = newImage("images/app_btn-over.gif");
		part_btn_over = newImage("images/part_btn-over.gif");
		about_btn_over = newImage("images/aboutus_btn-over.gif");
		trav_btn_over = newImage("images/travel1_btn-over.gif");
		preloadFlag = true;
	}
}