bug#17497: 24.4.50; TTY menu glitches

[Thomas Dickey <dickey@his.com>]

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On Sun, Jun 01, 2014 at 07:25:29PM +0300, Eli Zaretskii wrote:
> Emacs optimizes redrawing by comparing the previous and the desired
> display, and then only repainting the changed parts.

That's the intent - but
> 
> None of that changes when the menu is displayed, we just overwrite
> portions of the desired display data structure, then call the normal
> redrawing routines.  That's why it puzzles me why the problems are
> being reported only for the menus.

I downloaded tscript3.xz from message #50, and am cat'ing it (slowly)
to a 24x80 xterm.  It very clearly is not repainting just changed portions.
At the very beginning of the script, the screen updates just a couple of
lines (old/new) as the cursor moves across menu items.  But as soon as
the cursor goes past the menu items which are first shown, the program
is repainting the entire menu.  Thereafter, even after it has returned
to the original view, there are occasional repaints of the entire menu,
as well as cursor movement to/from the "Close" entry.

Most of the file, however, consists of repainting the menu.

-- 
Thomas E. Dickey <dickey@invisible-island.net>
http://invisible-island.net
ftp://invisible-island.net

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