Tracking script for AdSense

[Noël®]

Hi all,

I'm using the following code to track clicks on one of my sites that is
running AdSense.

<script type="text/javascript"><!--

function hit() {
window.focus();
if (window.status) {
img = new Image();
img.src = 'log.cfm?ref=' + escape(document.location) + '&link=' +
escape(window.status);
};
};
document.getElementById("google_ads_frame").onfocus = hit;

//--></script>

All is working fine in IE (The log.cfm file keeps track of everything), but
NOT in Opera and Mozilla Firfox (and I guess some other browsers)

The problem is I think the "onFocus" event handler.

Any suggestions on how I can get this small bit of code to work with more
browsers?

Small note. The code you see is placed right after the AdSense code itself
and there are no changes made in the AdSense code itself.

Noel