function changePage ( select_form, gita_id ) {
  switch ( select_form.options[select_form.selectedIndex].value ) {
    case "1":  // foto via e-mail
      open_external_link(select_form,"gite.php?id="+gita_id+"&mode=album&send");
      break;
    case "7":  // panorami a 360°
      open_external_link(select_form,"gite.php?id="+gita_id+"&mode=album#pano");
      break;
    case "8":  // video
      open_external_link(select_form,"gite.php?id="+gita_id+"&mode=album#video");
      break;

    case "2":  // commenta
      open_internal_link("commenta");
      break;
    case "3":  // vota la gita
      open_internal_link("sondaggio");
      break;
    case "4":  // mappe
      open_internal_link("mappe");
      break;
    case "5":  // link
      open_internal_link("link");
      break;
    case "6":  // su Google Maps
      open_internal_link("maps");
      break;
  }
}
function open_external_link ( select_form, url ) {
  select_form.disabled = true;
  document.location.href = url;
}
function open_internal_link ( id ) {
  document.getElementById("qui_"+id).style.display = "block";

  var qui_layers = new Array("commenta","sondaggio","mappe","link","maps");
  for ( i = 0; i < qui_layers.length; i++ ) {
    if ( id != qui_layers[i] && document.getElementById("qui_"+qui_layers[i]) != undefined ) {
      document.getElementById("qui_"+qui_layers[i]).style.display = "none";
    }
  }
  document.location.href = "#"+id;
}