TYPO3 Core

The first list (<ul>) you output from class.ext_update.php gets converted to jQuery tabs.
This forces you to use tabs, even if you don't want to.
(or use this workaround:

$content .= '<script type="text/javascript">jQuery(function(){jQuery("#typo3-extension-configuration-forms").tabs("destroy");});</script>';

this can be easily fixed by removing the call to:

$("#typo3-extension-configuration-forms").tabs();

in: /typo3/sysext/extensionmanager/Resources/Public/JavaScript/main.js