Out of curiosity, what's the practical difference between TUI and GUI when it comes to discoverability? The kinds of TUI I'm familiar with - mostly from DOS, so stuff like e.g. Borland IDEs (and various third party apps written using Turbo Vision), FoxPro, and VB for DOS - are essentially the same as GUI in that regard; you get a drop-down menu on top, windows with various widgets, often a help bar at the bottom and/or context-sensitive help with F1 etc.