Sorry. Didn't know that I could ask on Mantis - will have to find out how to do that.
The use case is pretty simple and "normal" I believe. This is a problem whenever your using/working with multi/sub-object materials where one of the materials needs displacement. In my case I work a lot with city models, where both terrain and buildings are build as large meshes with multi/sub-object materials assigned to then. In these situations it's almost impossible to use the Corona-Multimap workaround, and detaching the mesh-parts to single objects doesn't cut it either.
In earlier (Alpha) versions of Corona this wasn't a problem, so I hoped it could be fixed.
Regards