How to capture change in URL from BHO?

How can I capture a change in the URL on IE from a Browser Helper Object?

An obvious way would be to use 开发者_StackOverflowany of the common browser events such as onbeforenavigate, but how to capture a change like:

url.com#hello

changes to

url.com#byebye

Does this kind of change triggers any event on Internet Explorer?

onhashchange event introduced only in IE8, so you must check location on timer to handle url changes.