title: PHP output buffering callback yielding blank screen
body: <p>Here is the code:</p>
  
  <pre><code> ob_start(array(&amp;$dispatcher, 'outputCallback')); 
   include($file);
   ob_end_flush();
  
   function outputCallback($string) {
      if(ob_get_level() == 1) { 
          $static =&amp; ParserStatic::getInstance();
          return $static-&gt;insertToppings($string);
      }
      return false;
    }
  </code></pre>
  
  <p>The problem is when I return <code>$string</code> it behaves OK, but when it executes 
  the object assignment, it gives a blank screen. What's going wrong?</p>