This module defines a "button" object for use with the TV window
interface. A TV_float (a "changeable" TV_button) inherits all of
the functionality of the TV_button class, with the additional
functionality of being able to change its appearance
by reading from the "TV" screen. Limits can be placed on the
number read from the screen. These limits are in the form of a
delta (+/- from the original value).
V00.00 James Holt December 21, 1993
Original - cloned from tv_number.h.