function elShow(myElementName)  {
c = document.getElementById(myElementName);
c.style.visibility = "visible";
}
function elHide(myElementName)  {
c = document.getElementById(myElementName);
c.style.visibility = "hidden";
}
function elRoll(myElementName, newImage)  {
c = document.getElementById(myElementName);
c.setAttribute('src',newImage);
}