gistfile1.txt

function enable() {
    aggregateMenu = Main.panel.statusArea.aggregateMenu;

    if (aggregateMenu.hasOwnProperty('_volume') && aggregateMenu._volume instanceof PanelMenu.SystemIndicator) {
        volumeIndicator = aggregateMenu._volume;
        _onVolumeIndicatorScrollEventId = volumeIndicator.indicators.connect('scroll-event', _onVolumeIndicatorScroll);
        _onVolumeIndicatorClickEventId = volumeIndicator.indicators.connect('button-press-event', _onVolumeIndicatorClick);
        _onAggregateMenuEnterEventId = aggregateMenu.menu.actor.connect('enter-event', _onAggregateMenuEnter);
        _onAggregateMenuLeaveEventId = aggregateMenu.menu.actor.connect('leave-event', _onAggregateMenuLeave);
        _onAggregateMenuClickEventId = aggregateMenu.actor.connect('button-press-event', _onAggregateMenuClick);
    }
}

Yeah the same thing. You need just _power indicator and connect scroll event to another _brightness._proxy.Brightness = percent;