bug#17497: 24.4.50; TTY menu glitches

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 01 Jun 2014 13:18:17 -0400
> From: Thomas Dickey <dickey@his.com>
> Cc: Eli Zaretskii <eliz@gnu.org>, 17497@debbugs.gnu.org
> 
> What ncurses does when it's getting behind is to drop updates - the
> typeahead feature:
> 
>        The  curses  library does ``line-breakout optimization'' by looking for
>        typeahead periodically while updating the screen.  If input  is  found,
>        and  it is coming from a tty, the current update is postponed until re-
>        fresh or doupdate is called again.  This allows faster response to com-
>        mands  typed  in  advance.   Normally, the input FILE pointer passed to
>        newterm, or stdin in the case that initscr was used, will be used to do
>        this typeahead checking.  The typeahead routine specifies that the file
>        descriptor fd is to be used to check for typeahead instead.  If  fd  is
>        -1, then no typeahead checking is done.

So buffering output more aggressively could help, is that what you are
saying?

We currently fflush the stream every 900 bytes and also every 10
screen lines or so.  Does that sound reasonable?