function buttonOn (imgName) {
	if(document.images)  {
		buttonover = eval(imgName + "_on.src");
		document[imgName].src = buttonover;
	}
}

function buttonOff (imgName) {
	if(document.images) {
		buttonnormal = eval(imgName + "_off.src");
		document[imgName].src = buttonnormal;
	}
}