From 395ea6687b2dfa334bcafcc2a78c81032ca15bd0 Mon Sep 17 00:00:00 2001
From: nicm <nicm@openbsd.org>
Date: Mon, 28 Sep 2026 10:10:16 +0000
Subject: [PATCH] Fix floating panes not being detected as obscuring the pane
 behind them, GitHub issue 5641 from Michael Grant.

(cherry picked from commit bbecdc802fd79c0917a9bc742a29aa2b94afcdfc)
---
 screen-write.c | 12 ++----------
 tmux.h         |  4 +++-
 window.c       | 30 +++++++++++++++++++++++++++++-
 3 files changed, 34 insertions(+), 12 deletions(-)

diff --git a/screen-write.c b/screen-write.c
index 1b101ed94..c84e6e5fd 100644
--- a/screen-write.c
+++ b/screen-write.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: screen-write.c,v 1.290 2026/08/24 15:05:26 nicm Exp $ */
+/* $OpenBSD: screen-write.c,v 1.294 2026/09/28 10:10:16 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -199,15 +199,7 @@ screen_write_pane_is_obscured(struct screen_write_ctx *ctx)
 	}
 
 	while ((wp = TAILQ_PREV(wp, window_panes, zentry)) != NULL) {
-		if (window_pane_is_floating(wp) &&
-		    ((wp->yoff >= ctx->wp->yoff &&
-		    wp->yoff <= ctx->wp->yoff + (int)ctx->wp->sy) ||
-		    (wp->yoff + (int)wp->sy >= ctx->wp->yoff &&
-		    wp->yoff + wp->sy <= ctx->wp->yoff + ctx->wp->sy)) &&
-		    ((wp->xoff >= ctx->wp->xoff &&
-		    wp->xoff <= ctx->wp->xoff + (int)ctx->wp->sx) ||
-		    (wp->xoff + (int)wp->sx >= ctx->wp->xoff &&
-		    wp->xoff + wp->sx <= ctx->wp->xoff + ctx->wp->sx))) {
+		if (window_pane_floating_overlaps(wp, ctx->wp)) {
 			ctx->flags |= SCREEN_WRITE_OBSCURED;
 			return (1);
 		}
diff --git a/tmux.h b/tmux.h
index 4555fea2b..d58c40aa3 100644
--- a/tmux.h
+++ b/tmux.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: tmux.h,v 1.1447 2026/09/22 14:10:26 nicm Exp $ */
+/* $OpenBSD: tmux.h,v 1.1449 2026/09/28 10:10:16 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -3729,6 +3729,8 @@ struct window_pane *window_find_string(struct window *, const char *);
 int		 window_has_floating_panes(struct window *);
 int		 window_has_pane(struct window *, struct window_pane *);
 int		 window_pane_contains(struct window_pane *, u_int, u_int);
+int		 window_pane_floating_overlaps(struct window_pane *,
+		     struct window_pane *);
 int		 window_set_active_pane(struct window *, struct window_pane *,
 		     int);
 void		 window_fire_pane_moved(struct window_pane *, struct window *,
diff --git a/window.c b/window.c
index b8d9606be..dba25aba1 100644
--- a/window.c
+++ b/window.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: window.c,v 1.380 2026/09/28 09:56:05 nicm Exp $ */
+/* $OpenBSD: window.c,v 1.381 2026/09/28 10:10:16 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -667,6 +667,34 @@ window_pane_contains(struct window_pane *wp, u_int x, u_int y)
 	return (1);
 }
 
+/*
+ * Does floating pane, including its borders and scrollbar, overlap any cell of
+ * another pane, including its scrollbar?
+ */
+int
+window_pane_floating_overlaps(struct window_pane *fwp, struct window_pane *wp)
+{
+	int	fxoff, fyoff, xoff, yoff, border = 0;
+	u_int	fsx, fsy, sx, sy;
+
+	if (!window_pane_is_floating(fwp))
+		return (0);
+
+	window_pane_full_size_offset(fwp, &fxoff, &fyoff, &fsx, &fsy);
+	window_pane_full_size_offset(wp, &xoff, &yoff, &sx, &sy);
+
+	if (window_pane_get_pane_lines(fwp) != PANE_LINES_NONE)
+		border = 1;
+
+	if (fxoff - border >= xoff + (int)sx ||
+	    fxoff + (int)fsx + border <= xoff)
+		return (0);
+	if (fyoff - border >= yoff + (int)sy ||
+	    fyoff + (int)fsy + border <= yoff)
+		return (0);
+	return (1);
+}
+
 void
 window_update_focus(struct window *w)
 {