// Browser independent function to grab an object by its ID
function get_layerId(ElementName) {
   var layerId;
   if (document.getElementById) {
      layerId = eval('document.getElementById(ElementName)');
   }
   else if (document.all) {
      layerId =  eval('document.all[ElementName]');
   }
   else if (document.layers) {
      layerID =  eval('document.layers[ElementName]');
   }
   return layerId;
}

function hidePopup(popID) {
   var poppedLayer = get_layerId(popID);
   poppedLayer.style.visibility = "hidden";
   poppedLayer.style.display = "none";
   return false;
}