The newest version of my CoreData model requires a somewhat lengthy migration. If documents are large enough, a progress window should be shown. That's fine when the app is running and the user opens an old document. But when the state of the app is being restored, and any of the restored documents need to be migrated, changes to the app's window state appears to be frozen or something, because no amount of window manipulation I've tried during this time every shows up onscreen. The result is a long migration process with no user-visible activity in the app because. This is unacceptable.
Any ideas about how to show some UI during state restoration? NSUserNotification only works if the app is in the background, right? And it's not in the background after the user launches it, so the notification never appears.