We have been creating our own decendant of NSViewComponent to get some custom cocoa classes going. At first it did not seem to work as all what was shown was a black frame. We of course thought that was our own fault but when trying to embed the WebbrowserComponent we had the same result, as someone already found out.
For some reason i had the idea that it might had to-do with the main window not having a native title bar and voila after setting this to true it all worked. So were happy now, but this needs a fix of course.