From what I read in another thread, the earlier keys had a button for the rear glass. Someone had posted that they ordered an extra key, and when they picked it up, it had the extra button. I hear that they removed the button because people were inadvertently pressing the button instead of the button for the entire rear hatch.
In my Summit, when I press the button(on the hatch)for the rear glass, I hear it unlatching, but it does not noticeably pop-up. Also, yes, there is a lip on the rear wiper assembly to pull up the rear glass... PICS... Lip, closed, popped open.