var Ajax;
if (Ajax && (Ajax != null)) {
    Ajax.Responders.register({
        onCreate: function() {
            if ($('spinner') && Ajax.activeRequestCount > 0)
                Effect.Appear('spinner', {duration:0.5,queue:'end'});
        },
        onComplete: function() {
            if ($('spinner') && Ajax.activeRequestCount == 0)
                Effect.Fade('spinner', {duration:0.5,queue:'end'});
        }
    });
}