Tk 8.4 features three new widgets:

A spinbox is an extended entry widget that allows the user to move, or "spin," through a fixed set of values, such as times or dates, in addition to editing the value as in an entry.
A labelframe is very similar to the standard frame, but also has the ability to display a label. (TIP #18)
A panedwindow contains any number of panes, arranged horizontally or vertically. Each pane contains one widget, and each pair of panes is separated by a moveable sash, which causes the widgets on either side of the sash to be resized. (TIP #41)