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These routines set options that deal with output within curses. All options are initially FALSE, unless otherwise stated. It is not necessary to turn these options
off before calling endwin().
With the clearok() routine, if enabled (bf is TRUE), the next call to wrefresh() with this window will clear the screen
completely 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.
With the idlok() routine, if enabled (bf is TRUE), curses considers using the hardware insert/delete line feature of
terminals so equipped. If disabled (bf is FALSE) , curses very seldom uses this feature. (The insert/delete character feature
is always considered.) This option should be enabled only if the application needs insert/delete line, for example, for a screen editor. 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 cannot be used, curses redraws the changed portions of all lines.
With the idcok() routine, if enabled (bf is TRUE), curses considers using the hardware insert/delete character feature
of terminals so equipped. This is enabled by default.
With the immedok() routine, if enabled (bf is TRUE), any change in the window image, such as the ones caused by waddch(), wclrtobot(), wscrl(), etc., automatically cause a call to wrefresh(). However, it may degrade the 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 cursor 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 application 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 up one 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), wrefresh() is called on the window, and the physical terminal and window are scrolled up one line. (Note that in order to get the physical scrolling effect on the terminal,
it is also necessary to call idlok().)
The nl() and nonl() routines control whether newline is translated into carriage return and linefeed on output, and whether return is translated into newline
on input. Initially, the translations do occur. By disabling these translations using nonl(), curses is able to make better use of the linefeed capability, resulting
in faster cursor motion.
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