Redirect to Previous Page in Magento Admin – How to Guide

Just change the option:

System > Config > Customer 
> Costumer Redirect Customer to Account Dashboard after Logging in > NO

As all the comments stated before, its not out of the box. Here are some hints on where/what you may need to adjust:

Mage_Admin_Model_User

public function getStartupPageUrl()
    {
        $startupPage = Mage::getStoreConfig(self::XML_PATH_STARTUP_PAGE);
        $aclResource = 'admin/' . $startupPage;
        if (Mage::getSingleton('admin/session')->isAllowed($aclResource)) {
            $nodePath = 'menu/' . join('/children/', explode('/', $startupPage)) . '/action';
            $url = (string)Mage::getSingleton('admin/config')->getAdminhtmlConfig()->getNode($nodePath);
            if ($url) {
                return $url;
            }
        }
        return $this->findFirstAvailableMenu();
    }

I have never tried it but this seems to be the method called from

Mage_Adminhtml_IndexController

and there is the IndexAction that calls the above function. Since this is the admin, doing a rewrite of the Model will probably be easier.

/**
 * Admin area entry point
 * Always redirects to the startup page url
 */
public function indexAction()
{
    $session = Mage::getSingleton('admin/session');
    $url = $session->getUser()->getStartupPageUrl();
    if ($session->isFirstPageAfterLogin()) {
        // retain the "first page after login" value in session (before redirect)
        $session->setIsFirstPageAfterLogin(true);
    }
    $this->_redirect($url);
}

So, modifying getStartupPageUrl() to have your URL seems very likely the best place to try this.

This is all theoretical, I have not tried it yet, but if you need a sample module, I can certainly run through this and provide it.

If every admin user will end up on the same page, its pretty easy to do, if there is some dynamic elements, it will be a bit harder to facilitate. Good Luck!