// Pre-loading images
	
var button_homeOn = new Image()             
button_homeOn.src = "images/buttons/button_homeOn.jpg"; 
	
var button_homeOff = new Image()
button_homeOff.src = "images/buttons/button_homeOff.jpg";

var button_registerOn = new Image()             
button_registerOn.src = "images/buttons/button_registerOn.jpg"; 
	
var button_registerOff = new Image()
button_registerOff.src = "images/buttons/button_registerOff.jpg";

// functions for swapping
function showOn(imgName) { 
document.images[imgName].src = eval(imgName + "On.src")
}

function showOff(imgName) {
document.images[imgName].src = eval(imgName + "Off.src");
}