Scope Inside A Prototyped Function?

I'm trying to access some of the global's inside my class LiveSearch
and I have no idea how to go about it. Here is what I have so far:

<script type="text/javascript" src="query.js"></script>
<script type="text/javascript">
function LiveSearch(global) {
this.theglobal = global;
this.initialize();
}

LiveSearch.prototype.initialize = function() {
$("#thebutton").mousedown(function() { //when we click the button
alert(this.theglobal);
});
}

$(document).ready(function() {
var objSearch = new LiveSearch("globalvalue");
});
</script>

On page load I create a new LiveSearch instance and it assigns
theGlobal = "globalvalue" and proceeds to initialize(); At this point
Im using JQuery to setup an onmousedown event on a button on my page
with id="thebutton". When I click the button the alert comes back with
'undefined'. How can I get direct access to my theglobal variable? Code: