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			Curses Overview

The X/Open Curses Interface Definition describes a set of C-Language
functions that provide screen-handling and updating, which are
collectively known as the curses library.

The curses library permits manipulation of data structures called
windows which may be thought of as two-dimensional arrays of
characters representing all or part of a terminal's screen.  The
windows are manipulated using a procedural interface described
elsewhere.  The curses package maintains a record of what characters
are on the screen.  At the most basic level, manipulation is done with
the routines move() and addch() which are used to "move" the curses
around and add characters to the default window, stdscr, which
represents the whole screen.

An application may use these routines to add data to the window in any
convenient order.  Once all data have been added, the routine
refresh() is called.  The package then determines what changes have
been made which affect the screen.  The screen contents are then
changed to reflect those characters now in the window. using a
sequence of operations optimised for the type of terminal in use. 

At a higher level routines combining the actions of move() and addch()
are defined, as are routines to add whole strings and to perform
format conversions in the manner of printf(). 

Interfaces are alse defined to erase the entire window and to specify
the attributes of individual characters in the winodw.  Attributes
such as inverse video, underline and blink can be used on a
per-character basis. 

New windows can be created by allowing the application to build
several images of the screen and display the appropriate one very
quickly.  New windows are created using the routine newwin().  For
each routine that manipulates the default window, stdscr, there is a
corresponding routine prefixed with w to manipulate the contents of a
specified window; for example, move() and wmove().  In fact, move(...)
is functionally equivalent to wmove( stdscr, ...).  This is similar to
the interface offered by printf(...) and fprintf(stdout, ...). 

Windows do not have to correspond to the entire screen.  It is
possible to create smaller windows, and also to indicate that the
window is only partially visible on the screen.  Furthermore, large
windows or pads, which are bigger than the actual screen size, may be
created. 

The routine newterm() may be called to "open" additional terminals by
large applications wishing to manipulate several terminals at once.
The set_term() function is used to select the terminal whose screen is
to be updated by the next refresh(). 

Interfaces are also defined to allow input character manipulation and
to disable and enable many input attributes: character echo, single
character input with or without signal processing (cbreak or raw
modes), carriage returns mapping to newlines, screen scrolling, etc. 

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