title: Google Checkout : Best way to handle cart editing and checkout confirmation
body: <p>I am in the process of implementing Google Checkout in an e-store. Once customers click the 'Google Checkout' button, my project requires that they are able to navigate back to the e-store to possibly edit the cart. Customers should be able to click the 'back' button, type in the URL to my cart page, or click the 'edit' link from Google.</p>
  
  <p>At the same time, I need to clear the cart and provide customers with a blank slate as soon as they click the confirmation button on Google's side. I am already listening for a new-order-notification from Google, but this does not always arrive quickly enough to prevent customers from returning to the e-store and scratching theirs heads as to why their carts still show the items they just purchased.</p>
  
  <p>Have any Google Checkout implementors come up with a novel solution to this problem? Any ideas are appreciated!</p>