The PayPal API has what's commonly referred to as a "Thank You page" -- basically a redirect page, after the user's gone through the Google Checkout process. What is the equivalent parameter to pass this value to via Google Checkout's XML API?
(I notice that their integration flow ends after redirecting the user to the Google checkout page. Is such not possible?)
-- Update
It looks like adding the following to the initial XML send puts a small link "Return to [Merchant Name]" on the final order page - is there a way to change [Merchant Name], and or, having the page redirect (rather than just link) back to the a custom thank you page?
<checkout-flow-support>
<merchant-checkout-flow-support>
<continue-shopping-url>
http://redirecturl.example.com
</continue-shopping-url>
</merchant-checkout-flow-support>
</checkout-flow-support>