The black bars are still bugged if you switch from windowed to fullscreen, but the game at least remembers the setting now, and the bars work properly if the game starts in full screen (and don't alt+tab out), so that's progress.
Also, while messing with alt+tabbing, I noticed that after pressing alt in the chat part of the intro sequence, you can press X to quit the chat and hide the phone, and then you'll be unable to do anything and have to close the game. Is this a debug feature or some really weird bug? Also, the FPS Counter option in the settings menu is mislabeled as Full screen as well.
Sorry about the late response by the way, I've been away from my desktop (and will be away for a good while again).