Para detener el burbujeo no es mejor esto?:
Código PHP:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>TEST</title>
<script>
function mmousedown(e)
{
var evt = e ? e : window.event;
alert('dentro de pepe');
if (evt.cancelBubble==false) {
evt.cancelBubble=true;
}
if(evt.stopPropagation && evt.stopPropagation()==undefined) {
evt.stopPropagation();
}
}
function test(){alert('fuera de pepe');}
</script>
</head>
<body>
<div id="pepe" style="cursor:pointer; background-color:#CCCCCC; border:1px solid #000000">testear</div>
<script>
document.getElementById('pepe').onmousedown = mmousedown;
document.onmousedown=test;
</script>
</body>
</html>