Mac OS X Developer Preview 3 is the third Developer Preview of Mac OS X Public Beta. This build was first demonstrated at the Mac OS X introduction on 2000-01 in MacWorld 2000 and in MacWorld Expo 2000 in Tokyo on 2000-02-16.
This Developer Preview, compiled on 2000-01-31, is notable for major interface overhauls; most notably the debut of the Aqua theme. In addition, a prototype version of the Dock is included, which was implemented to help users switch to other programs that are running. Other changes includes new icons that revolves around on skeuomorphism and additional changes to the upper menu bar.