libRUIN (Renderer for User Interfaces in Ncurses) is a rendering library for various XML-based user interface markup languages (such as Mozilla XUL), using the Ncurses (http://www.gnu.org/software/ncurses/) terminal control library as a rendering target. GNU Guile (http://www.gnu.org/software/guile/) and the SDOM (http://www.nongnu.org/sdom/) Scheme module are used as the "glue" that manages user input and event handling. An application programmer passes an XML document (including, potentially, a set of CSS stylesheets) and an Ncurses WINDOW structure, and libRUIN paints the WINDOW according to the markup and CSS; the programmer may subsequently pass Ncurses-style input strings to that WINDOW via libRUIN, and libRUIN will handle the resulting event flows.