what are the two arrows on the top right of each window? Thay make the screen huge..
They are a part of 10.8. Known as 'full screen mode' they enlarge a window to the entire size of the screen and remove any unwanted distractions so you can focus on your application.
Click once to enable and then again to disable.
Is there key command associated with it?
Not that I know of off the top of my head. You could look in your System Preferences > Keyboard and see if you can find/create a shortcut but I don't think it's possible.
control-command-F is the shortcut
...and Escape (esc key in the upper left of the keyboard) will take you out of Full Screen.
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