Text UI (TUI or Text User Interface) is a rich user interface based on text terminal windows as opposed to graphics in GUI or simple scrolling commandl-line interface, CLI.
Most TUI systems appeared to mimic already existing GUIs, so they often feature screen elements like panels, title bars, and controls like buttons, edits boxes, etc. The screen elements have absolute positions and user input has focus, which moves between the elements.
Implementation of popular TUIs like Turbo Vision and curses is based on screen and its elements having character and attribute (foreground and background colors) matrices populated with API commands and an engine that composes these boxes and renders on the screen.
tui_proto.ijs is a prototype, which provides a high level API with put using text coordinates, verbs to generate framed boxes and rulers, which populate internal rectangle; and an engine that renders the rectangle to gl2 canvas. A different engine would render the same box into text terminal.