They changed their software to (or from?) OpenGL, which uses a different method to make the events transparent. Basically, from what I have gathered Steinberg will only bring back transparent events on C6 if enough people bitch about it. Best thing anyone can do at this point is e-mail Steinberg or make an account on their forum and complain about the lack of transparent events. If enough people are unhappy about it they might change it, I have a feeling not enough people will though and it'll go unchanged.
EDIT: ^^^^ register and post in that thread!!!
EDIT: ^^^^ register and post in that thread!!!