Editing MacOS version history (section)

===Changed direction under Jobs===
Apple's financial losses continued and the board of directors lost confidence in CEO [[Gil Amelio]], asking him to resign. The board asked [[Steve Jobs]] to lead the company on an interim basis, essentially giving him ''[[wikt:carte blanche|carte blanche]]'' to make changes to return the company to profitability. When Jobs announced at the [[Apple Worldwide Developers Conference|World Wide Developer's Conference]] that what developers really wanted was a modern version of the Mac OS, and Apple was going to deliver it{{Citation needed|date=February 2009}}, he was met with applause.

Over the next two years, a major effort was applied to porting the original Macintosh API to Unix libraries known as ''[[Carbon (computing)|Carbon]]''. Mac OS applications could be ported to Carbon without the need for a complete re-write, making them operate as native applications on the new operating system. Meanwhile, applications written using the older toolkits would be supported using the "Classic" Mac OS 9 environment. Support for [[C (programming language)|C]], [[C++]], [[Objective-C]], [[Java (programming language)|Java]], and [[Python (programming language)|Python]] were added, furthering developer comfort with the new platform.{{Citation needed|date=February 2021}}

During this time, the lower layers of the operating system (the [[Mach (kernel)|Mach kernel]] and the BSD layers on top of it<ref>A Practical Guide to Linux Commands, Editors, and Shell Programming, 3rd edition by Mark G. Sobell, page 2</ref>) were re-packaged and released under the [[Apple Public Source License]]. They became known as [[Darwin (operating system)|Darwin]]. The Darwin kernel provides a stable and flexible operating system, which takes advantage of the contributions of programmers and independent open-source projects outside Apple; however, it sees little use outside the Macintosh community.{{Citation needed|date=December 2017}}

During this period, the [[Java (programming language)|Java programming language]] had increased in popularity, and an effort was started to improve Mac Java support. This consisted of porting a high-speed Java [[virtual machine]] to the platform, and exposing macOS-specific "Cocoa" APIs to the Java language.{{Citation needed|date=February 2021}}

The first release of the new OS — [[Mac OS X Server 1.0]] — used a modified version of the Mac OS GUI, but all client versions starting with Mac OS X Developer Preview 3 used a new theme known as [[Aqua (user interface)|Aqua]]. Aqua marked a significant shift from the Mac OS 9 interface, which had seen minimal changes since the original Macintosh OS. It introduced full-color scalable graphics, text and graphic anti-aliasing, simulated shading and highlights, transparency, shadows, and animation. A new feature was the Dock, an application launcher which took advantage of these capabilities.

Despite this, Mac OS X maintained a substantial degree of consistency with the traditional Mac OS interface and Apple's own [https://web.archive.org/web/20110805043358/http://developer.apple.com/library/mac/#documentation/UserExperience/Conceptual/AppleHIGuidelines/Intro/Intro.html Apple Human Interface Guidelines], with its pull-down menu at the top of the screen, familiar keyboard shortcuts, and support for a single-button mouse. The development of Aqua was delayed somewhat by the switch from OpenStep's [[Display PostScript]] engine to one developed in-house that was free of any license restrictions, known as [[Quartz (graphics layer)|Quartz]].{{Citation needed|date=February 2021}}