Insert a line above the line containing the current cursor
    position. The insertln function acts on the stdscr window.

    Format

      #include  <curses.h>

      int insertln();

      int winsertln  (WINDOW *win);

1  –  Argument

 win

    A pointer to the window.

2  –  Description

    The current line and every line below it shifts down, and the
    bottom line disappears. The inserted line is blank and the
    current (y,x) coordinates remain the same. For more information,
    see the scrollok function.

3  –  Return Values

    OK                 Indicates success.
    ERR                Indicates that the function makes the screen
                       scroll illegally.