void clear_message_window()
{
   PCHAR_INFO pci = screen + SCREENINDEX(0, VIEW_EY);
   const int ncols = get_number_of_cols();
   for (int x = 0; x < ncols; x++)
   {
      for (int y = 0; y < get_message_window_height(); y++)
      {
         pci->Char.AsciiChar = ' ';
         pci->Attributes = 0;
         pci++;
      }
   }
   COORD source;
   SMALL_RECT target;
   source.X = 0;
   source.Y = VIEW_EY;
   target.Left = 0;
   target.Top = VIEW_EY;
   target.Right = get_number_of_cols() - 1;
   target.Bottom = get_number_of_lines() - 1;
   WriteConsoleOutput(outbuf, screen, screensize, source, &target);
}
extern int get_message_window_height();
static void scroll_message_buffer()
{
    memmove( screen + SCREENINDEX(0, VIEW_EY),
             screen + SCREENINDEX(0, VIEW_EY + 1),
             get_message_window_height() * get_number_of_cols() 
                                         * sizeof(*screen) );
}
static void scroll_message_window()
{
    SMALL_RECT scroll_rectangle, clip_rectangle;
    scroll_rectangle.Left   = 0;
    scroll_rectangle.Top    = VIEW_EY + 1;
    scroll_rectangle.Right  = get_number_of_cols() - 1;
    scroll_rectangle.Bottom = get_number_of_lines() - 1;
    clip_rectangle          = scroll_rectangle;
    clip_rectangle.Top      = VIEW_EY;
    COORD new_origin;
    new_origin.X            = 0;
    new_origin.Y            = VIEW_EY;
    CHAR_INFO fill;
    fill.Char.AsciiChar     = ' ';
    fill.Attributes         = WIN32COLOR(LIGHTGREY);
    ::ScrollConsoleScreenBuffer(
            outbuf, &scroll_rectangle, &clip_rectangle,
            new_origin, &fill);
    scroll_message_buffer();
    // Cursor also scrolls up so prompts don't look brain-damaged.
    if (wherey() == get_number_of_lines())
        gotoxy(wherex(), wherey() - 1);
}
void message_out(int which_line, int colour, const char *s, int firstcol,
                 bool newline)
{
    if (!firstcol)
        firstcol = Options.delay_message_clear? 2 : 1;
    gotoxy(firstcol, which_line + VIEW_EY + 1);
    textcolor(colour);
    cprintf("%s", s);
    if (newline && which_line == get_message_window_height() - 1)
        scroll_message_window();
}