The Tix library has, by far, the greatest collection of widgets for
programming with Tcl/Tk. Highlights include: hierarchical list box,
directory list/tree view, spreadsheet, tabular list box, combo box,
Motif style file select box, MS Windows style file select box, paned
window, note book, spin control widget and many more. With these new
widgets, your applications will look great and interact with your users
in intuitive ways.