Bumping this up as I need to know too. We will be arriving about 10 PM, and the parks are open till midnight. Will the ticket windows still be open? We want to go to MM the next morning, which starts at 7 AM, so we want to have our tickets ready. Thanks.
Since I hadn't received a reply I called Disney this morning. The answer was that the windows will open within 15' of the park opening. If it is a MM it will open at that time. Unfortunately this will put you behind for the entering of the park.
He did report that at least one window would be open the entire time the park will be open. If you can go over the night before to get tickets so you could enter on time for the next morning.