>>I´ve never done it before, but I have seen a rasterized curves file and the curves are very complex, aren´t they? Maybe it is a problem for work with that curves.....what do you think?

Surely, but there is a couple of commands in Rhino to reconstruct complex curves - FitCrv, SimplifyCrv, Rebuild, MakePeriodic...on the other side, window transparency application is quite "chic" for MoI.

Petr