title: Chrome extension open new window behind the current window
body: <p>i have a chrome extension which automatically open a window using 
      window.open();
  when user open some specific websites.
  what i want is the new window which i open from the background script through window.open() should be displayed behind the current webiste opened by the user.</p>
  
  <p>i have tried window.open properties like alwaysLowered=1, z-lock=1 etc. but not working.
  Also tried.....</p>
  
  <pre><code>var w = window.open('url');
  if(w){
  w.blur();
  window.focus();
  }
  </code></pre>
  
  <p>all these have no effect on chrome. can anybody help?</p>