Yes, matching C enums and Nim enums needs some care. In your case, I have the feeling that RendererFlip should be a Nim set from the beginning. As it looks like a bitset which can be empty, bit 0 can be set, or bit 1 can be set.
I did that for a few types in gintro. Generally enums not starting at 0 are a problem in Nim too, I had to add dummy 0 values in gintro. And I think that enums with holes will vanish in Nim some day, I think they are already deprecated. But I think in gintro we had no enums with holes. Araq sometimes recommends using distinct int constants instead of enums in Nim. But for gintro enums and sets of enums work fine.
