Fx.Scroll.scrollToCenter

Fx.Scroll.implement({
    scrollToCenter: function(el, axes, offset){
        axes = axes ? $splat(axes) : ['x', 'y'];
        el = $(el);
        var to = {},
            pos = el.getPosition(this.element),
            size = el.getSize(),
            scroll = this.element.getScroll(),
            containerSize = this.element.getSize(),
            edge = {
                x: pos.x + size.x,
                y: pos.y + size.y
            };
            
        ['x','y'].each(function(axis){
            if(axes.contains(axis)){
                to[axis] = pos[axis] - (containerSize[axis] - size[axis])/2;
            }
            if(to[axis] == null) to[axis] = scroll[axis];
            if(offset && offset[axis]) to[axis] = to[axis] + offset[axis];
        }, this);
        if (to.x != scroll.x || to.y != scroll.y) this.start(to.x, to.y);
        return this;
    }
});