// BrowserCheck Object
function BrowserCheck()
{
    var b = navigator.appName

    if (b == "Netscape") {
        this.b = "ns";
    } else if (b=="Microsoft Internet Explorer") {
        this.b = "ie";
    } else {
        this.b = b;
    }

    this.version    = navigator.appVersion;
    this.v          = parseInt(this.version);
    this.ns         = (this.b == "ns" && this.v >= 4);
    this.ns4        = (this.b == "ns" && this.v == 4);
    this.ns5        = (this.b == "ns" && this.v == 5);
    this.ie         = (this.b == "ie" && this.v >= 4);
    this.ie4        = (this.version.indexOf('MSis.ie 4') > 0);
    this.ie5        = (this.version.indexOf('MSis.ie 5') > 0);
    this.min        = (this.ns || this.ie);
}
is = new BrowserCheck();

self.onError    = null;
diffY           = 0;
lastScrollY     = 0;
var defaultTop  = 550;
<!-- STALKER CODE -->
function heartBeat()
{
    if (is.ie) {
        diffY = document.body.scrollTop;
    }
    if (is.ns) {
        diffY = self.pageYOffset;
    }
    if ( diffY != lastScrollY ) {
        deltaY = diffY - lastScrollY;
        document.getElementById("icon_topDiv").style.top = parseInt( defaultTop + lastScrollY + deltaY ) + 'px';
        lastScrollY = diffY;
    }
}
function startStalker()
{
    if (is.min) {
        window.setInterval("heartBeat()", 1);
    } 
}