having issues with onbeforeunload. I have a long form broken into segments via a jquery wizard plug in. I need to pop a confirm dialog if you hit back, refresh, close etc on any step but need it to NOT POP the confirm dialog on click of the submit button. had it working, or at least I thought, it doesn't now.

<script type="text/javascript">
var okToSubmit = false;
window.onbeforeunload = function() {
document.getElementById('Register').onclick = function() { okToSubmit = true; };
if(!okToSubmit) return "Using the browsers back button will cause you to lose all     form data. Please use the Next and Back buttons on the form"; 
};
</script>

'Register' is the submit button ID. Please help!