I upgraded fro C4D R11.5 to Studio R12.
I have a strange problem with alpha channel in the preview Windows.
In OpenGL, after some manipulations (rotate view, etc...) the alpha channel doesn't work anymore.
I tried on 3 different computers, (XP, Seven 64b)with the same effect.
No problem with C4D R11.5 with the same config.
Here is the MAXON response: "there have been some customers telling us of this issue, but none of our machines was able to reconstruct
the issue. However, even if there would be a bug, all you can do is switching off OpenGL and wait for a new version
that would fix the problem."
I liked the idea of switching off OpenGL and back to the old software rendering.
C4D R13 is coming and I doubt there will be other updates to R12.