From 035a2f35d40628dcfe235179220fc0ede848a195 Mon Sep 17 00:00:00 2001
From: nicm <nicm>
Date: Tue, 6 Jan 2026 14:33:05 +0000
Subject: [PATCH] Clear trimmed lines after moving, from Antony Raj in GitHub
 issue 4790.

---
 grid.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/grid.c b/grid.c
index 63eea68d..7ad6770b 100644
--- a/grid.c
+++ b/grid.c
@@ -361,9 +361,13 @@ grid_compare(struct grid *ga, struct grid *gb)
 static void
 grid_trim_history(struct grid *gd, u_int ny)
 {
+	u_int	remaining;
+
 	grid_free_lines(gd, 0, ny);
+	remaining = gd->hsize + gd->sy - ny;
 	memmove(&gd->linedata[0], &gd->linedata[ny],
-	    (gd->hsize + gd->sy - ny) * (sizeof *gd->linedata));
+	    remaining * (sizeof *gd->linedata));
+	memset(&gd->linedata[remaining], 0, ny * (sizeof *gd->linedata));
 }
 
 /*