tk_scale (title, scale_1, ...)
scale = legend, initial_value, min, max , resolution
display N vertical scales, each one labeled with legend; each scale is
initially set to initial_value, and its value can span from min to
max in resolution increments.
E.g.: [eta lamb mu] = tk_scale('Scale Demo', 'eta', 3, 1, 10, 0.1,
'lambda', 4, 2, 20, 1, 'mu', 0.01, 0.001, 0.1, 0.01)