title: Set custom page title with hook
body: <p>I'm trying to set a custom page title (<code>&lt;title&gt;&lt;/title&gt;</code>) with <code>wp_title</code>.</p>
  
  <p>The simplest function in the world:</p>
  
  <pre><code>function sweety_page_title($string)
  {
      echo $string . ' - ';
  }
  </code></pre>
  
  <p>After I call:</p>
  
  <pre><code>do_action('wp_title', 'my title...');
  add_action('wp_title', 'sweety_page_title', 10, 1);
  </code></pre>
  
  <p>But it does not work.</p>
  
  <p>Where am I wrong?</p>