function popupWindow(url) {
  window.open(url,'popupWindow','toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=no,resizable=yes,copyhistory=no,width=400,height=300,screenX=150,screenY=150,top=150,left=150')
}

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) {
		botones_01_over = newImage("img/botones-01_over.gif");
		botones_02_over = newImage("img/botones-02_over.gif");
		botones_03_over = newImage("img/botones-03_over.gif");
		preloadFlag = true;
	}
}