In 10.8 I have to get the bitmapData each time I want to write directly in the bitmap of an NSBitmapImageRep I created with my own space in -initWithBitmapDataPlanes. I compile against SDK 10.5. The result of -bitmapData is constant changing. This wasn't the case in 10.4 to 10.7. If write to the space I allocated and set in -initWithBitmapDataPlanes no result is displayed. What changed in 10.8 causing this?