Wavelength Change by Refraction

[PearCoding]

The change of the wavelength when a refraction occurs is not taken care of when intersecting with another surface, while being inside the diffracted domain. This is not visible on a glass sphere, but if something is inside of it, the calculation will get wrong. See for example the front-page screen-shot where water is on top of the floor. The returned reflection color is wrong.
The wavelength in vacuum has to be available all the time, as the index of refraction is calculated by it regardless of the media, but also the wavelength inside media has to be available at least when shading, as spectral lookups have to be done with this wavelength.
Adding this support is worth only when volume is added. IOR should be handled by two media intersecting (e.g. glass material)