A/UX and the Macintosh operating system are two distinct entities. The
user boots the Macintosh II either into the Macintosh OS or into A/UX.
One operating system is not a window or shell in another. Each stands
alone.
A/UX includes Macintosh ToolBox support. Thus, an A/UX application might
LOOK like a Macintosh application, with windows, menus, and so on. In fact,
a "well-behaved" Macintosh application can be ported to A/UX and run under
UNIX using the same toolbox calls it did under the Macintosh operating
system.