How to show / hide navigation to avoid cycling from beginning to end of content

Hi

I was just wondering if anyone else has manged to get the scroll buttons to show / hide depending on the position you are within the stream of content being passed through the Ajax scroller? Im trying to hide the up / down button when at the beginning / end of the content to avoid cycling around.

Ive used a really simple javascript method but its doesnt seem to have any effect on the navigation buttons.

Has anyone else tried to achieve this? Im using the rss functionality to pull a twitter list through at dorkingcc.co.uk

Any thoughts v welcome

Kate

Example javascript added to page via mod_ajaxscroller.php (added to page via $content .=' ';
<script>
function toggle_show(id)
{ var el = document.getElementById(id);
if (el && el.style){
el.style.display = el.style.display == "none" ? "block" : "none";
} }
toggle_show(mNavUp104);
</script>