Subject: Re: bug#17497: 24.4.50; TTY menu glitches

From: Thomas Dickey <[email-masked]>
Date: Sun, 01 Jun 2014 13:18:17 -0400

On Sun, Jun 01, 2014 at 01:12:44PM -0400, Thomas Dickey wrote:
> Most of the file, however, consists of repainting the menu.

By the way, since the menu covers only half the screen, there aren't
any general-purpose scrolling optimizations that would help.  (xterm
does support left/right margins, which would be interesting to explore
in this area).  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.

-- 
Thomas E. Dickey <[email-masked]>
http://invisible-island.net
ftp://invisible-island.net