I've got a small libcurses test program that dumps core when linked with
electric fence:

% cat test-border.c
#include <curses.h>
#include <stdlib.h>
#include <unistd.h>

int
main()
{
    initscr();
    border(0,0,0,0,0,0,0,0);
    refresh();
    sleep(5);
    endwin();
    exit(0);
}

% gcc -Wall -g test-border.c -lcurses
% ./a.out
<displays a nice border for 5 seconds>

% gcc -Wall -g test-border.c -lcurses -L/usr/local/lib -lefence
% gdb a.out
(gdb) run
Program received signal SIGSEGV, Segmentation fault.
0x4806da3d in doupdate () from /usr/lib/libcurses.so.5
(gdb) bt
#0  0x4806da3d in doupdate () from /usr/lib/libcurses.so.5
#1  0x4806d09a in doupdate () from /usr/lib/libcurses.so.5
#2  0x4806cd93 in wrefresh () from /usr/lib/libcurses.so.5
#3  0x4806c823 in refresh () from /usr/lib/libcurses.so.5
#4  0x8048e50 in main () at test-border.c:10
#5  0x8048ae4 in ___start ()


It crashes under both 2.0_BETA and 3.99.5.  I've done some initial
debugging on the 2.0 box.  At the end of border.c:

/* Corners */
if (!(win->maxx == LINES && win->maxy == COLS &&
            ^^^^^^^^^^^^^         ^^^^^^^^^^^^
       (win->flags & __SCROLLOK) && (win->flags & __SCROLLWIN))) {
    fp[0].ch = (wchar_t) topleft & __CHARTEXT;
    fp[0].bch = win->bch;
    fp[0].attr = (attr_t) topleft & __ATTRIBUTES;
    fp[0].battr = win->battr;
    fp[endx].ch = (wchar_t) topright & __CHARTEXT;
    fp[endx].bch = win->bch;
    fp[endx].attr = (attr_t) topright & __ATTRIBUTES;
    fp[endx].battr = win->battr;
    lp[0].ch = (wchar_t) botleft & __CHARTEXT;
    lp[0].bch = win->bch;
    lp[0].attr = (attr_t) botleft & __ATTRIBUTES;
    lp[0].battr = win->battr;
// lp[endx].ch = (wchar_t) botright & __CHARTEXT;
// lp[endx].bch = win->bch;
// lp[endx].attr = (attr_t) botright & __ATTRIBUTES;
// lp[endx].battr = win->battr;
}
__touchwin(win);
return (OK);


The test looks wrong, maxy == LINES && maxx == COLS would be more
intuitive.  This change didn't make any difference.

Commenting out the last 4 lines allows the program to run under
electric fence, with and without the previous change.

Any other suggestions before I send-pr?

-Neil