function openWindow($page, $width, $height) {
  window.open($page, 'popup','width=$width,height=$height,toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=yes');
}

function showElement(name){
  var w = document.getElementById(name);
  w.style.display = 'block';
}       

function hideElement(name) {
  document.getElementById(name).style.display = 'none';
}