<script>
function updateApparition(c, i) {

  var name = c.prefix + i;

  moveLayer(name, randomX(c), randomY(c));

  setVisible(name, true);

  var delay = random(c.randomInterval);

  setTimeout('setVisible("' + name + '", false)', delay);

  setTimeout('updateApparition(c' + c.uid + ',' + i + ')', delay + c.minInvisibleTime + random(c.randomInterval));

}
</script>