function roll(img_name, img_src)
{
	document.getElementById(img_name).src = img_src;
}

function toggleShowOrHide(obj)
{
	var el = document.getElementById(obj);
	if ( el.style.display != 'none' ) {
		el.style.display = 'none';
	}
	else {
		el.style.display = '';
	}
}