A gamma curve widget.. Rather complex.
Lets the user edit a gamma curve (a one-to-one mapping usually used
to adjust the intensity of an image to the physical characteristics
of the output device). You can set the minimum and maximum values
for input and output. You can set the initial vector as well. You
are guaranteed that every input value will have a (not necessarily
unique) output value specified.
GTK.GammaCurve()->set_usize(210,130)
GTK.GLArea()->wait_gl()