Magento: Form key in backend

Sometime you try to catch the submit url to handle your request in backend.
E.g. http://localhost/Magento/admin/assign_theme/approve/id/10

You look at the controller and find you have already declare the delete action as

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class Pamysoft_AssignTheme_IndexController {     public function approve()     {          echo 'The approving processing should go here!'; exit;     } }

Solution:
Add the hidden input form_key to make your form submit correctly

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$formKey = Mage::getSingleton('core/session')->getFormKey();   <input type="hidden" name="form_key" value="<?php echo $formKey; ?>" />;