code: public static function getThemes()
  	{
  		$arrReturn = array();
  		$rootDir = System::getContainer()->getParameter('kernel.project_dir');
  		$arrThemes = scan($rootDir . '/system/themes');
  
  		foreach ($arrThemes as $strTheme)
  		{
  			if (strncmp($strTheme, '.', 1) === 0 || !is_dir($rootDir . '/system/themes/' . $strTheme))
  			{
  				continue;
  			}
  
  			$arrReturn[$strTheme] = $strTheme;
  		}
  
  		return $arrReturn;
  	}
docs: Return the back end themes as array
  
  @return array An array of available back end themes