No new actions in Magento CE 1.3

Please, add the line
Mage::dispatchEvent('adminhtml_block_salesrule_actions_prepareform', array('form' => $form));

right before the line
$form->setValues($model->getData());

in the file
app\code\core\Mage\Adminhtml\Block\Promo\Quote\Edit\Tab\Actions.php

This version of Magento have this line by default, so you can upgrade it freely.