What is the TUI menu and how is it used?

The TUI is the Text User Interface, which is an alternate to the GUI (Graphical User Interface). It was designed for use in planetariums where the UI has to be as unobtrusive as possible if projected on the dome.

To enter or leave the TUI, hit 'm' (for "menu"). The menu structure is a tree with two levels, sections and items. Use the up and down arrow keys to navigate between the top level sections or between items if already within a particular section. Use the right and left arrow keys to go between sections, items, and editing the value of an item.

While editing you can hit Enter to finish editing, or Esc to cancel your edit. If you want to have your changes persist for your next session, be sure to save your configuration as your default using TUI item 8.2 (section 8, item 2).