Tweak is a graphical user interface

Graphical user interface

In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...

 (GUI) layer to the Squeak

Squeak

The Squeak programming language is a Smalltalk implementation. It is object-oriented, class-based and reflective.It was derived directly from Smalltalk-80 by a group at Apple Computer that included some of the original Smalltalk-80 developers...

 development environment, which in turn is an integrated development environment

Integrated development environment

An integrated development environment is a software application that provides comprehensive facilities to computer programmers for software development...

 based on the Smalltalk

Smalltalk

Smalltalk is an object-oriented, dynamically typed, reflective programming language. Smalltalk was created as the language to underpin the "new world" of computing exemplified by "human–computer symbiosis." It was designed and created in part for educational use, more so for constructionist...

-80 computer programming language

Programming language

A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....

. Tweak is an alternative to an earlier graphic user interface layer called Morphic

Morphic (software)

The name "Morphic" was taken from the Greek word "morph", its morphs taking on the role of "forms", the basic graphical building blocks in earlier Self systems and in Smalltalk MVC....

. Development began in 2001.

Applications that use the Tweak software include Sophie (version 1), a multimedia and e-book authoring system, and a family of virtual world systems: Open Cobalt

Open Cobalt

Open Cobalt is a free and open source software platform for constructing, accessing, and sharing virtual world both on local area networks or across the Internet, without any requirement for centralized servers....

, Teleplace and the Croquet Project

Croquet Project

The Croquet Project was an international effort to promote the continued development of the Croquet open source software development kit for creating and delivering deeply collaborative multi-user online applications....

. An experimental version of Etoys

EToys (Programming Language)

Etoys is a child-friendly computer environment and object-oriented prototype-based programming language for use in education.Etoys is a media-rich authoring environment with a scripted object model for many different objects that runs on different platforms and is free and open source.- Brief...

used Tweak instead of Morphic.