How can I update window.location.hash without jumping the document?

Question

I have a sliding panel set up on my website.

When it finished animating, I set the hash like so

function() {
   window.location.hash = id;
}

(this is a callback, and the id is assigned earlier).

This works good, to allow the user to bookmark the panel, and also for the non JavaScript version to work.

However, when I update the hash, the browser jumps to the location. I guess this is expected behaviour.

My question is: how can I prevent this? I.e. how can I change the window's hash, but not have the browser scroll to the element if the hash exists? Some sort of event.preventDefault() sort of thing?

I'm using jQuery 1.4 and the scrollTo plugin.

Many thanks!

Update

Here is the code that changes the panel.

$('#something a').click(function(event) {
    event.preventDefault();
    var link = $(this);
    var id = link[0].hash;

    $('#slider').scrollTo(id, 800, {
        onAfter: function() {

            link.parents('li').siblings().removeClass('active');
            link.parent().addClass('active');
            window.location.hash = id;

            }
    });
});