Q:

Magento: Which is the controller for address changes in admin area? 

Which is the controller that is used when an address is changed from the order view in the admin area?  I thought it was Addresscontroller.php, but it isnt.  
Any ideas? 

A:

If you look closely, there is a request url which updates address when you save address from sales order grid : 

youradminhandle/sales_order/addressSave/address_id/123/key/3werg01875bfbe163fee7c8e2c4ade0a3547

here the controller will be inside 

app\code\core\Mage\Adminhtml\controllers\Sales\OrderController.php

where you need to check 

addressSaveAction()

