MAC Operating System Question:

You have to go to options and then go to graphic options and click on the windowed mode. If it is lighted up it means it will be minimized. If it is minimized it means you can do anything you can usually do on your computer, but if for example you open safari it will pause the game. If it is not lit up it will be full screen and you wont be able to do anything else but aoe3. The graphics are better in full screen though.