Just a slight correction, Blue Box was a version of the classic environment that only ran full screen. It only made it as far as some of the developer previews.

Just a slight correction, Blue Box was a version of the classic environment that only ran full screen. It only made it as far as some of the developer previews. When Aqua was announced, it became the classic environment, where classic apps could be run along side modern cocoa apps without having to switch full screen between the blue box and the NeXT-derived OS.