function backToTop() {
    var x1 = x2 = x3 = 0;
    var y1 = y2 = y3 = 0;

    if (document.documentElement) {
        x1 = document.documentElement.scrollLeft || 0;
        y1 = document.documentElement.scrollTop || 0;
    }

    if (document.body) {
        x2 = document.body.scrollLeft || 0;
        y2 = document.body.scrollTop || 0;
    }

    x3 = window.scrollX || 0;
    y3 = window.scrollY || 0;

    var x = Math.max(x1, Math.max(x2, x3));
    var y = Math.max(y1, Math.max(y2, y3));

    window.scrollTo(Math.floor(x / 2), Math.floor(y / 2));

    if (x > 0 || y > 0) {
        window.setTimeout("backToTop()", 25);
    }
}

function popup(winname, url, winopt){

  // Center the popup window
  var winwidth      = 624;
  var winheight     = 500;
  var desktopHeight = screen.availHeight;
  var desktopWidth  = screen.availWidth; 

  var top   = (desktopHeight - winheight) / 2;
  var left  = (desktopWidth - winwidth) / 2;

  var urlPrefix = "";
  var winurl    = url;

  //var winname   = "popup";
  //var winopt    = "toolbar=0,location=0,directories=0,status=0,menubar=0,scrollbars=1,copyhistory=0,resizable=0,width="+winwidth+",height="+winheight+",left="+left+",top="+top;
  var newwin    = window.open(winurl,winname,winopt);

}