How to automatically login a web user after registration?

require 'webloginpe.class.php';

class WebloginPEextended extends WebloginPE
{
	/**
	 * TriggerLogin
	 * Perform all the necessary functions to establish a secure user session with permissions
	 * Similar to Login() but works manually
	 * (instead of processing username/password from $_POST it takes username/password arguments) 
	 *	 
	 * @param string $username
	 * @param string $password
	 * @return void
	 * @author Johan "MrDutchy" van den Broek
	 */
	function TriggerLogin($username, $password, $customTable = 'web_user_attributes_extended')
	{
		global $modx;
		$this->CustomTable($customTable,'');
		$this->Username = $modx->db->escape(strip_tags($username));
		$this->Password = $modx->db->escape(strip_tags($password));
		if ($this->Username == '' || $this->Password == '')
			return;			
		$this->OnBeforeWebLogin();
		$this->User = $this->QueryDbForUser($this->Username);
		if ($this->User == false)
			return;
		$this->UserIsBlocked();
		$this->Authenticate();
		$this->SessionHandler('start');
		$this->OnWebLogin();
		$this->ActiveUsers();
		$this->UserDocumentGroups();
	}
}

include_once MODX_BASE_PATH.'assets/snippets/webloginpe/lang/de.php';
include_once MODX_BASE_PATH.'assets/snippets/webloginpe/webloginpe.extended.class.php';

if (count($_POST) > 0 && isset($_POST['doDummy']))
{
  $wlpe = new WebLoginPE($wlpe_lang);
  return $wlpe->TriggerLogin('mywebuser', 'mypassword');
}
else
{
  return
'<form action="" method="post">
<input type="submit" name="doDummy" value="doDummy" />
</form>';
}

$user = $hook->getValue('register.user');
if ($user == null) { return false; }
  
$modx->user =& $user;
$modx->getUser();

$contexts = !empty($scriptProperties['authenticateContexts']) ? $scriptProperties['authenticateContexts'] : $modx->context->get('key');
$contexts = explode(',',$contexts);
  foreach ($contexts as $ctx) {
  $user->addSessionContext($ctx);
}

return true;