var preloaded = [];

preloaded[1]=[loadImage("nv/5.jpg"), loadImage("nv/5o.jpg")];

function init() {

if (mtDropDown.isSupported()) {
mtDropDown.initialize();

menu1.onactivate = function() { swapImage("button1", preloaded[1][1].src) };
menu1.ondeactivate = function() { swapImage("button1", preloaded[1][0].src) };

}
}

function loadImage(sFilename) {
	var img = new Image();
	img.src =sFilename;
	return img;
}

function swapImage(imgName, sFilename) {
	document.images[imgName].src = sFilename;
}