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.