           clearok,   idlok,   idcok   immedok,  leaveok,  setscrreg,
           wsetscrreg, scrollok, nl, nonl - curses output options

## SYNOPSIS

           #include <curses.h>

           int clearok(WINDOW *win, bool bf);
           int idlok(WINDOW *win, bool bf);
           void idcok(WINDOW *win, bool bf);
           void immedok(WINDOW *win, bool bf);
           int leaveok(WINDOW *win, bool bf);
           int setscrreg(int top, int bot);
           int wsetscrreg(WINDOW *win, int top, int bot);
           int scrollok(WINDOW *win, bool bf);
           int nl(void);
           int nonl(void);

## DESCRIPTION

           These routines set options that change the style of output
           within  curses.   All  options are initially FALSE, unless
           otherwise stated.  It  is  not  necessary  to  turn  these
           options off before calling endwin.

           If  clearok is called with TRUE as argument, the next call
           to wrefresh with this window will clear  the  screen  com-
           pletely  and  redraw the entire screen from scratch.  This
           is useful when the contents of the screen  are  uncertain,
           or  in  some  cases for a more pleasing visual effect.  If
           the win argument to clearok is the global variable curscr,
           the  next  call  to  wrefresh  with  any window causes the
           screen to be cleared and repainted from scratch.

           If idlok is called with TRUE as  second  argument,  curses
           considers using the hardware insert/delete line feature of
           terminals so equipped.  Calling idlok with FALSE as second
           argument  disables  use  of  line  insertion and deletion.
           This option should be  enabled  only  if  the  application
           needs  insert/delete  line, for example, for a screen edi-
           tor.  It is disabled by default because insert/delete line
           tends  to  be  visually annoying when used in applications
           where it isn't really needed.  If insert/delete line  can-
           not  be  used,  curses redraws the changed portions of all
           lines.

           If idcok is called with FALSE as second  argument,  curses
           no longer considers using the hardware insert/delete char-
           acter feature of terminals so equipped.  Use of  character
           insert/delete  is  enabled by default.  Calling idcok with
           TRUE as second argument re-enables use of character inser-
           tion and deletion.

           If  immedok is called with TRUE as argument, any change in
           fresh.  However, it may degrade performance  considerably,
           due  to  repeated  calls  to  wrefresh.  It is disabled by
           default.

           Normally, the hardware cursor is left at the  location  of
           the  window  cursor  being  refreshed.  The leaveok option
           allows the cursor to be left wherever the  update  happens
           to leave it.  It is useful for applications where the cur-
           sor is not used, since it  reduces  the  need  for  cursor
           motions.   If  possible, the cursor is made invisible when
           this option is enabled.

           The setscrreg and wsetscrreg routines allow  the  applica-
           tion  programmer  to  set a software scrolling region in a
           window.  top and bot are the line numbers of the  top  and
           bottom margin of the scrolling region.  (Line 0 is the top
           line of the window.)  If  this  option  and  scrollok  are
           enabled,  an  attempt  to  move off the bottom margin line
           causes all lines in the scrolling  region  to  scroll  one
           line in the direction of the first line.  Only the text of
           the window is scrolled.  (Note that this has nothing to do
           with  the use of a physical scrolling region capability in
           the terminal, like that in the VT100.  If idlok is enabled
           and   the  terminal  has  either  a  scrolling  region  or
           insert/delete line capability, they will probably be  used
           by the output routines.)

           The  scrollok option controls what happens when the cursor
           of a window is  moved  off  the  edge  of  the  window  or
           scrolling  region,  either as a result of a newline action
           on the bottom line, or typing the last  character  of  the
           last line.  If disabled, (bf is FALSE), the cursor is left
           on the bottom line.  If enabled, (bf is TRUE), the  window
           is  scrolled  up  one  line (Note that in order to get the
           physical scrolling effect on the terminal, it is also nec-
           essary to call idlok).

           The  nl  and  nonl routines control whether the underlying
           display device translates the return key into  newline  on
           input,  and  whether it translates newline into return and
           line-feed on output (in either case,  the  call  addch('0)
           does the equivalent of return and line feed on the virtual
           screen).  Initially, these translations do occur.  If  you
           disable  them using nonl, curses will be able to make bet-
           ter use of the line-feed capability, resulting  in  faster
           cursor  motion.   Also, curses will then be able to detect
           the return key.

## RETURN VALUE

           The functions setscrreg and wsetscrreg return OK upon suc-
           cess  and ERR upon failure. All other routines that return
           an integer always return OK.
           These functions are described in the XSI Curses  standard,
           Issue 4.

           The  XSI  Curses  standard is ambiguous on the question of
           whether raw() should disable the  CRLF  translations  con-
           trolled by nl() and nonl().  BSD curses did turn off these
           translations; AT&T curses (at least as late as  SVr1)  did
           not.   We choose to do so, on the theory that a programmer
           requesting raw input wants a clean (ideally  8-bit  clean)
           connection that the operating system does not mess with.

           Some  historic  curses  implementations had, as an undocu-
           mented feature,  the  ability  to  do  the  equivalent  of
           clearok(...,  1)  by saying touchwin(stdscr) or clear(std-
           scr).  This will not work under ncurses.

           Earlier System V  curses  implementations  specified  that
           with  scrollok enabled, any window modification triggering
           a scroll also forced a physical refresh.  XSI Curses  does
           not  require this, and ncurses avoids doing it in order to
           perform better vertical-motion  optimization  at  wrefresh
           time.

           The  XSI  Curses standard does not mention that the cursor
           should be made invisible  as  a  side-effect  of  leaveok.
           SVr4 curses does this.

## NOTES

           Note  that clearok, leaveok, scrollok, idcok, nl, nonl and
           setscrreg may be macros.

           The immedok routine is useful for windows that are used as
           terminal emulators.

## SEE ALSO

           curses(3X),         curs_addch(3X),        curs_clear(3X),
           curs_initscr(3X), curs_scroll(3X), curs_refresh(3X)