function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      if (oldonload) {
        oldonload();
      }
      func();
    }
  }
}

addLoadEvent(setupZoom);

/* add more functions to run on page load 

// http://en.wikipedia.org/wiki/Unobtrusive_JavaScript
// http://alistapart.com/articles/behavioralseparation
// http://simonwillison.net/2004/May/26/addLoadEvent/

*/