[Greasemonkey] A question about GM_xmlhttpRequest

[Rick Evans]

Given the following Greasemonkey script:

// ==UserScript==
// @name           test of GM_xmlhttpRequest
// @namespace      http://mywebsite.com/myscripts
// @description    A template for creating new user scripts from
// @include        *
// ==/UserScript==

  alert( 'message 1' );
  GM_xmlhttpRequest(
    {
      method:'GET',
      url:'http://greasemonkey.mozdev.org/',
      onload:function(details) {
        alert( 'message 2' );
      }
    }
  );
  alert( 'message 3' );

The alert messages come in the following order:

message 1
message 3
message 2

Is there a way to modify the behavior of the GM_xmlhttpRequest so that the
onload function must finish and alert 'message 2' execute before the script
continues with the 3rd alert message?

Thanks for any insight you can provide.

Rick