OS X Mavericks includes a huge overhaul to multiple displays. Previous versions of OS X would dedicate primary and secondary displays where only one of the displays has a menu bar and Dock. Mavericks removes that limitation and now includes a menu bar and Dock on each screen. Moving the mouse cursor to the bottom of any window will bring up the Dock.

Setting an application to full-screen mode will now only use the display where the application is currently located. This is a welcomed improvement over previous OS X versions where putting an application into full-screen mode resulted in all other displays becoming unusable and showing only a cross-thatched linen background.

Here is an example of the Finder window in full-screen mode on one display and Microsoft Word, iTunes, and Messages on the secondary display.

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In OS X Mavericks all other displays are left available. Each display also has its own Mission Control; they are no longer automatically switched when changing Desktops.

One downside of the new approach to multiple displays is that one application window can no longer span multiple displays.

Here is an example of Mission Control for two displays.
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