Since 1990's Windows 3, Alt-Tab has enabled users to easily switch between running applications. Apple added the feature using Command-Tab in Mac OS X 10.3 Panther in 2003. In recent versions, the command brings up a horizontal menu of icons. Apple, however, added functionality -- the ability to navigate the menu with the Command and arrow keys -- that Microsoft copied and added to Vista. Windows Vista also added previews of the windows themselves with the Flip 3D feature in the Aero theme.
