window.addEvent('domready', function() {
    $$('.nspMainPortalMode2 .nspBotInterface .nspNext').each(function(el) {
        //fx
        var fx = new Fx.Tween(el,{
            duration: 220,
            link: 'cancel'
        });
        
        //css & events
        el.setStyle('background-position','-50px -48px').addEvents({
            'mouseenter': function(e) {
                e.stop();
                fx.start('background-position','0 -48px');
            },
            'mouseleave': function(e) {
                e.stop();
                fx.start('background-position','-50px -48px');
            }
        });
    });
    
    /* example b:  right left */
    $$('.nspMainPortalMode2 .nspBotInterface .nspPrev').each(function(el) {
        //css
        var reset = false;
        var fx = new Fx.Tween(el,{
            duration: 220,
            link: 'cancel',
            onComplete:function() {
                if(reset) {
                    el.setStyle('background-position','0 0');
                }
            }
        });
        //events
        el.setStyle('background-position','0 0').addEvents({
            'mouseenter': function(e) {
                e.stop();
                fx.start('background-position','-50px 0');
                reset = false;
            },
            'mouseleave': function(e) {
                reset = true;
                fx.start('background-position','0 0');
            }
        });
    });
    
});