How do we exclude the cart and checkout from a customized theme?

Question

Is there a simple way to exclude the customized theme from the cart and checkout page (however still keeping the customized theme's header and footer). I simply want the original RWD design one from my magento 1.9.1

Answer 1

The Right Way™ to do this would be to actually forcefully change the design package and theme from within a layout observer to the default RWD theme whenever the cart or checkout layout handles exist. You would call your observer on the layout_load_before event:

<?php

class Demo_Module_Model_Observer
{

    public function layoutLoadBefore()
    {
        $checkoutHandles = ['checkout_cart_index', 'checkout_onepage_index'];
        $activeHandles = Mage::app()->getLayout()->getUpdate()->getHandles();

        if(in_array($checkoutHandles, $activeHandles)){

            Mage::getDesign()->setArea('frontend')
                ->setPackageName('rwd')
                ->setTheme('default');
        }

        return $this;
    }

}

Answer 2

Remove the checkout folder from the template folder in your custom theme and remove checkout.xml from your custom theme layout folder.