var preloaded = [];

preloaded[1]=[loadImage("i/7.gif"), loadImage("i/7ov.gif")];
preloaded[2]=[loadImage("i/11.gif"), loadImage("i/11ov.gif")];
preloaded[3]=[loadImage("i/13.gif"), loadImage("i/13ov.gif")];

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) };

menu2.onactivate = function() { swapImage("button2", preloaded[2][1].src) };
menu2.ondeactivate = function() { swapImage("button2", preloaded[2][0].src) };

menu3.onactivate = function() { swapImage("button3", preloaded[3][1].src) };
menu3.ondeactivate = function() { swapImage("button3", preloaded[3][0].src) };

}
}

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

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