title: window.open cache problem
body: <p>I'm using <strong><em>window.open</em></strong> in a function to open a web page, which displays help for the 
  current page.</p>
  
  <p>The pages URL are stored in DB , some pages need authentication.</p>
  
  <p>For these pages, the first time we call them the user has to authenticate, but if he closes the page and opens it another time , it's the cached page that is displayed.</p>
  
  <p>I've try to add the time to the url, in order to not display the cached page</p>
  
  <pre><code>var oDate = new Date();
  window.open(url+oDate.getTime());
  </code></pre>
  
  <p>But the browser is still displaying the cached url.</p>
  
  <p>Any idea to resolve this problem?</p>
  
  <p>Thanks.</p>