Libgreattao is framework to build app by simple gives information about possible actions to framework. Of course, programmer could also set icon, shortcut, etc., but Libgreattao is able to built UI by information about possible action. It's possible thanks to window class files, which contains templates and UI elements. Each action have weight, which allow to decide, which template use. In fact, /actions/app/exit could have weight 1 and /actions/files/open could have weight 0, so prior is added additionally to toolbar and second will be added only to app menu. Libgreattao app have many backends (GTK+, Qt, TUI and shell). Shell is console shell - you can work with program interactively by setting value of action path and invoke actions. You can also wrote a script to control application.