var currentElement;
var currentLink;

function showElement(id, anchor_id) {
   if (currentElement) hideElement(currentElement);
   document.getElementById(id).style.display = "block";
   currentElement = id;
   document.getElementById(anchor_id).style.display = "none";
   if (currentLink) document.getElementById(currentLink).style.display = "inline";
   currentLink = anchor_id;
}
function hideElement(id) {
   document.getElementById(id).style.display = "none";
}