Full Screen Fix for Mac OS X Mavericks:
1) Start up 'System Preferences' > 'Displays'
2) Hold 'Option' key and mouse-click on Radio icon next to 'Scaled'
3) A list of additional resolutions will be available to choose from. You want to pick the highest resolution possible, while following the 4:3 screen aspect ratio.
List of resolutions with Display Aspect Ratio of 4:3 to try:
800x600 (not good for AC Lobby)
1344x1008 (this is my highest resolution, which I use for my widescreen monitor)