These functions set options that deal with the output within Curses functions.
The clearok() function assigns the value of bf to an internal flag in the specified window that governs clearing of the screen during a refresh. If, during
a refresh operation on the specified window, the flag in curscr is TRUE or the flag in the specified window is TRUE, clearok()
clears the screen, redraws it in its entirety, and sets the flag to FALSE in curscr and in the specified window. The initial state is unspecified
The idlok() function specifies whether the implementation may use the hardware insert-line, delete-line, and scroll features of terminals so equipped. If bf
is TRUE, use of these features is enabled. If bf is FALSE, use of these features is disabled and lines are instead redrawn as required. The
initial state is FALSE.
The leaveok() function controls the cursor position after a refresh operation. If bf is TRUE, refresh operations on the specified window
may leave the terminal's cursor at an arbitrary position. If bf is FALSE, then at the end of any refresh operation, the terminal's cursor is positioned at the
cursor position contained in the specified window. The initial state is FALSE.
The scrollok() function controls the use of scrolling.If bf is TRUE, then scrolling is enabled for the specified window. If bf is FALSE, scrolling is disabled for the specified window. The initial state is FALSE.
The setscrreg() and wsetscrreg() functions define a software scrolling region in the current or specified window. The top and bottom arguments are the line numbers of the first and last line defining 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 last line of the margin causes all lines in the scrolling region to scroll one line in the direction of the first line. Only characters in the window are scrolled. If
a software scrolling region is set and scrollok() is not enabled, an attempt to move off the last line of the margin does not reposition any lines in the scrolling region.