I seem to get some differences between what works in OpenGL on one machine and what works on another (both Mac's). On my ibook for example I can use glCopyPixels with a remapping of colors using tables (in glPixelTransfer GL_COLOR?) .. I try to copy the backbuffer on top of itself with color remapping. It works fine on the ibook (software opengl only), but it refuses to work on the imac. Also I found that in some cases I need to add extra glDisalble GL_TEXTURE_2D on the ibook but not on the imac. I don't know why it isn't consistent. Driver issues?