Focus tab or window

The following appears to work in IE8 and FF13:

<script type="text/javascript">
// Stupid script to force focus to an existing tab when the link is clicked.
// And yes, we do need to open it twice.
function openHelp(a) {
    var tab = window.open(a.href, a.target);
    tab.close();
    tab = window.open(a.href, a.target);
    return false;
}
</script>
<a href="https://stackoverflow.com/questions/8135188/help.html" target="help" onclick="return openHelp(this);">Help</a>