popupActive=false;
function showdiv(id)
{
  if (popupActive)
    return;
  var div     = document.getElementById(id);
  div.style.display='block';
  popupActive=true;
}
function hidediv(id)
{
  if (!popupActive)
    return;
  var div     = document.getElementById(id);
  div.style.display='none';
  popupActive=false;
}