<p>Allows the global template data to be manipulated. This is the data available to templates under the <code>{$xf}</code> param.</p>

<p>Callback signature:</p>
<blockquote><code><em>\XF\App</em> $app, <em>array</em> &amp;$data, $reply</code></blockquote>

<p>Arguments:</p>
<ol>
	<li><code><em>\XF\App</em> $app</code> - Global App object.</li>
	<li><code><em>array</em> &amp;$data</code> - Global template data.</li>
	<li><code>$reply</code> - This may contain the \XF\Mvc\Reply\AbstractReply object from the controller. It may not be available; null will be provided instead.</li>
</ol>