commit 88a4da97478ec6b4b2f361315a5a183333d0aa3f
Author: Nicholas Marriott <nicm@openbsd.org>
Date:   Wed May 15 15:39:51 2013 +0000

    Don't let cursor position overflow when reflowing, from Christopher
    Collins.

diff --git a/screen.c b/screen.c
index 754effc..76aa91c 100644
--- a/screen.c
+++ b/screen.c
@@ -365,7 +365,13 @@ void
 screen_reflow(struct screen *s, u_int new_x)
 {
 	struct grid	*old = s->grid;
+	u_int		 change;
 
 	s->grid = grid_create(old->sx, old->sy, old->hlimit);
-	s->cy -= grid_reflow(s->grid, old, new_x);
+
+	change = grid_reflow(s->grid, old, new_x);
+	if (change < s->cy)
+		s->cy -= change;
+	else
+		s->cy = 0;
 }