NeWS window system extensions to the PostScript language.

=> Objects look like dictionaries.

=> Lightweight Processes

==> NeWS schedules many lightweight PostScript processes.
==> They all live together in the NeWS server's address space.
==> They're cheap!
==> Scheduling is non-preemptive.
==> Process groups.

==> A lightweight process consists of:
===> Graphics context
===> Execution stack
===> Dictionary stack
===> Operand stack

==> Lightweight processes are good for:
===> Servicing events.
===> Managing interactive objects.
===> Pre-processing local input on behalf of the client.
===> Performing background processing.
===> Building interactive graphical user interface toolkits.
===> Interactive animation.
===> And many other thinks too kinky to go into here.

=> Monitors
==> Synchronization.
==> Protect shared data structures.

=> Events
==> NeWS has an event queue, and a clean virtual event mechanism.
==> Input from hardware devices generates events.
==> NeWS processes can generate events.
==> NeWS processes can communicate with each other by sending events back 
and forth.
==> It's easy to simulated input from virtual devices.
==> Coordinates of events reported in the current coordinate system.
==> NeWS processes express interest in events they want to get.
===> Event matching rules.
==> Events are used as interest templates.
==> Then they loop waiting for and processing such events.

=> Canvases
==> Drawing surface.
==> Arranged in a hierarchy.
==> Each has its own coordinate system.
==> Arbitrarily shaped!!!
==> Shape defined by a PostScript path.
==> Lines, arcs, bezier curves, and conic splines as edges.
==> Holes, and disconnected regions!
==> Shape influences the clipping of graphical output, and the distribution 
of input events.
==> Useful as arbitrarily shaped targets.
==> NeWS processes can receive input events whenever the mouse enters, 
leaves, clicks, or moves around in a canvas.
==> When a canvas is damaged, an event is generated which should cause
a process to repaint it.
==> Natural to use as animated "sprites", using NeWS processes to
periodically blink, move, or paint them.

=> Color
==> RGB
==> HSB

=> Garbage collection
==> Reference counts