You know, it's a different thing to assemble a list of all the features 3ds Max offers, and Corona does not support them, such as advanced nitrous viewport shading, material editor preview shapes, or for example exposure controls. But purpose of this section is to determine priority of features as well as to search for truly useful features that would improve workflow significantly.
So while it is always good to know what of these minor things are still missing, it might not be worth mentioning at this moment when there are obviously a lot more important things to implement. I think absence of various shapes in material editor preview is not really a dealbreaker for anyone who is seriously interested in Corona.
Best way to help is to try to come up with innovative features and solution that would improve workflow speed and/or efficiency as much as possible. It may even be things that no other renderer has yet, or things that other renderers have, but that could be done better, or more efficiently, or to be altered to server a lot wider range of purposes that it's original one.
A prime example is when AO pass was requested. Keymaster did some quick'n'dirty implementation of AO pass, but then we came out with a Texmap pass, which you can use to generate AO map if you put AO map into it, but also to generate whole range of different passes depending on which map you put there.
MR and Vray already had this, and it seemed to be a lot more universal solution.
So to wrap it up, best contribution is to come up with innovative features, or to find a new creative ways to extend current ones to increase their field of use. ;)
