function activate_page(element) {
    var tabs = document.getElementsByName("page_div");
    for (i = 0; i < tabs.length; i++) {
        tabs[i].className = "";
    }

    document.getElementById(element).className = "active";
}

Ajax.Responders.register({
  onCreate: function() {
    if($('busy_indicator') && Ajax.activeRequestCount>0)
      Effect.Appear('busy_indicator',{duration:1,queue:'begin'});
  },
  onComplete: function() {
    if($('busy_indicator') && Ajax.activeRequestCount==0)
      Effect.Fade('busy_indicator',{duration:1,queue:'begin'});
  }
});