It is an evolution of ClassAct, which is an object-oriented system of classes that enhanced the aspect of the Workbench 2.0 GUI of AmigaOS.
However, until AmigaOS 2.0 there was no standardized look and feel, and often application developers had to write their own non-standard widgets (both buttons and menus), with Intuition providing little support.
The introduction of BOOPSI allowed third-party developers to create comprehensive widget toolkits, such as MUI and ClassAct which later evolved into ReAction.
Programmers Christopher 'caldi' Aldi, Timothy Aston, Osma 'Tau' Ahvenlampi came together and ClassAct is a realization of that future.
The main purpose of this gadget is displaying data distribution among various sources, like shares, disk capacity and free space, etc.
Cygnix is a lightweight UNIX simulation environment for AmigaOS that comes with an X11 server Cygwin, and this has been used to port programs such as AbiWord or GIMP to the Amiga.