Adding external controls

I am attempting to add external controls (as on http://sorgalla.com/projects/jcarousel/examples/static_controls.html).

They work nicely by adding the following to the document head:

<style type="text/css">

/**
 * Additional styles for the controls.
 */
.jcarousel-control {
    margin-bottom: 10px;
    text-align: center;
}

.jcarousel-control a {
    font-size: 75%;
    text-decoration: none;
    padding: 0 5px;
    margin: 0 0 5px 0;
    border: 1px solid #fff;
    color: #eee;
    background-color: #4088b8;
    font-weight: bold;
}

.jcarousel-control a:focus,
.jcarousel-control a:active {
    outline: none;
}

.jcarousel-scroll {
    margin-top: 10px;
    text-align: center;
}

.jcarousel-scroll form {
    margin: 0;
    padding: 0;
}

.jcarousel-scroll select {
    font-size: 75%;
}

#mycarousel-next,
#mycarousel-prev {
    cursor: pointer;
    margin-bottom: -10px;
    text-decoration: underline;
    font-size: 11px;
}

</style>

<script type="text/javascript">
/**
 * We use the initCallback callback
 * to assign functionality to the controls
 */
function mycarousel_initCallback(carousel) {
    jQuery('.jcarousel-control a').bind('click', function() {
        carousel.scroll(jQuery.jcarousel.intval(jQuery(this).text()));
        return false;
    });

    jQuery('.jcarousel-scroll select').bind('change', function() {
        carousel.options.scroll = jQuery.jcarousel.intval(this.options[this.selectedIndex].value);
        return false;
    });

    jQuery('.jcarousel-next').bind('click', function() {
        carousel.next();
        return false;
    });

    jQuery('.jcarousel-prev').bind('click', function() {
        carousel.prev();
        return false;
    });
};

// Ride the carousel...
jQuery(document).ready(function() {
    jQuery(".jcarousel-container").jcarousel({
        scroll: 1,
        initCallback: mycarousel_initCallback,
        // This tells jCarousel NOT to autobuild prev/next buttons
        buttonNextHTML: null,
        buttonPrevHTML: null
    });
});

</script>

When the final item is reached, the 'next' arrow dims, has 'disabled= true' added to it, but it is still clickable and moves the slider on.

Do you have any idea how to fix this? It works really nicely apart from this little bug?

Thanks