Merge branch 'master' into redraw-damage-rectangles-new

OSS-Fuzz: Add new fuzzer targets json processing

.github/workflows/regress.yml

@@ -27,10 +27,10 @@ jobs:
             runner: ubuntu-24.04
             make: make
             configure: --enable-utf8proc --enable-asan
-          #- name: ubuntu-24.04-arm64
-          #  runner: ubuntu-24.04-arm
-          #  make: make
-          #  configure: --enable-utf8proc --enable-asan
+          - name: ubuntu-24.04-arm64
+            runner: ubuntu-24.04-arm
+            make: make
+            configure: --enable-utf8proc --enable-asan
           - name: macos-26-arm64
             runner: macos-26
             make: gmake
@@ -72,14 +72,14 @@ jobs:
 
       - name: build
         run: |
-         sh autogen.sh
+          sh autogen.sh
           ./configure ${{ matrix.configure }}
           ${{ matrix.make }} -j"$(getconf _NPROCESSORS_ONLN)"
 
       - name: test
         run: |
           cd regress
-          ${{ matrix.make }}
+          ${{ matrix.make }} -j"$(getconf _NPROCESSORS_ONLN)"
 
       - name: logs
         if: failure()

CHANGES

@@ -10,8 +10,8 @@ CHANGES FROM 3.7c TO 3.8
   - modal panes may be created with new-pane -O; a window can have one modal
     pane and it prevents interaction with the other panes while it is active.
     -C closes the pane when the mouse is clicked outside it and -K sends all
-    keys, including the prefix key, to the pane. A modal pane is now used for
-    the editor in buffer mode;
+    keys, including the prefix key, to the pane. -D closes the modal pane with
+    Escape or C-c. A modal pane is now used for the editor in buffer mode;
 
   - new-pane -A creates a floating pane which remains above a zoomed pane;
     modal panes do this by default;
@@ -39,6 +39,9 @@ CHANGES FROM 3.7c TO 3.8
   The old format is still accepted; control mode clients receive old layouts
   unless they set the new-layouts flag.
 
+* Add remain-on-exit failed-key to keep a pane open after a failed command
+  until a key is pressed.
+
 * Add support for themes and improve default colours:
 
   - tmux now has builtin light and dark colour themes for terminals with 256 or
@@ -115,6 +118,12 @@ CHANGES FROM 3.7c TO 3.8
   in terminal-features, and add a utf8 feature for terminals which support
   UTF-8 output.
 
+* Add an appesc terminal feature for mintty's application escape key mode,
+  avoiding unsupported sequences on other terminals (Pete Dietl, issue 5626).
+
+* Preserve existing Ss and Se terminfo capabilities for cursor styles and
+  restoring the default cursor (issue 5476).
+
 * Add a #{A/count:frames} modifier to show a series of frames as an animation
   in the status line (issue 5412 from Fernando Daciuk).
 
@@ -189,10 +198,23 @@ CHANGES FROM 3.7c TO 3.8
   sent inside %begin/%end (issue 5458), do not let a stuck client prevent the
   server from exiting (issue 5444), and reset control mode offsets when a pane
   is respawned (issue 5498). Bound buffered command replies so a control mode
-  client that stops reading cannot consume unlimited memory (issue 5565).
+  client that stops reading cannot consume unlimited memory (issue 5565), and
+  fix a collision between the output discard and bracketed paste flags (issue
+  5622).
 
 * Fix grouped sessions sometimes being left as unusable command targets while
-  they are being killed (Bryce Miller, issue 5180).
+  they are being killed (Bryce Miller, issue 5180), and prevent reuse of a
+  session with no windows while detaching (Heon Jeong, issue 5620).
+
+* Free wait-for clients when they disconnect and do not run their remaining
+  queued commands (issue 5614).
+
+* Expand formats in run-shell -c like other start-directory flags (reported by
+  Saul Nogueras).
+
+* Fix session alert flag formats to check all windows (issue 5599).
+
+* Do not clear the marked pane when clicking on a pane border.
 
 * Fix choose mode filtering when more than one pane exists (issue 5326), and
   fix an infinite loop in customize mode when a filter does not match.
@@ -203,11 +225,18 @@ CHANGES FROM 3.7c TO 3.8
   status lines, menus, popups, wide characters and floating panes. This
   includes fixes for flicker with alternate screen applications and scrollbars
   (Michael Grant, issue 5351; Noam Stolero, issue 5350; Aung Myo Kyaw, issue
-  5098).
+  5098), and misplaced wrapped lines during partial redraws (Ben Maurer, issue
+  5625).
 
 * Do not crash looking for the next or previous session (issue 5344), or when
   no client is available.
 
+* Fix crashes when destroying a zoomed pane (Romain Francoise, issue 5591),
+  copying from a blank source pane (Kaixuan Li), or opening a mode prompt when
+  the client is offset into the window.
+
+* Avoid an infinite loop when assigning a width to WCHAR_MAX (issue 5602).
+
 CHANGES FROM 3.7b TO 3.7c
 
 * Build with jemalloc on macOS to avoid what appears to be a bug in calloc

Makefile.am

@@ -15,6 +15,9 @@ AM_CPPFLAGS += @XOPEN_DEFINES@ \
 	-DTMUX_LOCK_CMD='"@DEFAULT_LOCK_CMD@"' \
 	-DTMUX_TERM='"@DEFAULT_TERM@"' \
 	-DTMUX_MOUSE=1
+if HAVE_TMUX_SOCK
+AM_CPPFLAGS += -DTMUX_SOCK='"@TMUX_SOCK@"'
+endif
 
 # Additional object files.
 LDADD = $(LIBOBJS)
@@ -257,7 +260,9 @@ check_PROGRAMS = \
 	fuzz/input-fuzzer \
 	fuzz/cmd-parse-fuzzer \
 	fuzz/format-fuzzer \
-	fuzz/style-fuzzer
+	fuzz/style-fuzzer \
+	fuzz/layout-fuzzer \
+	fuzz/json-fuzzer
 fuzz_input_fuzzer_LDFLAGS = $(FUZZING_LIBS)
 fuzz_input_fuzzer_LDADD = $(LDADD) $(tmux_OBJECTS)
 fuzz_cmd_parse_fuzzer_LDFLAGS = $(FUZZING_LIBS)
@@ -266,6 +271,10 @@ fuzz_format_fuzzer_LDFLAGS = $(FUZZING_LIBS)
 fuzz_format_fuzzer_LDADD = $(LDADD) $(tmux_OBJECTS)
 fuzz_style_fuzzer_LDFLAGS = $(FUZZING_LIBS)
 fuzz_style_fuzzer_LDADD = $(LDADD) $(tmux_OBJECTS)
+fuzz_layout_fuzzer_LDFLAGS = $(FUZZING_LIBS)
+fuzz_layout_fuzzer_LDADD = $(LDADD) $(tmux_OBJECTS)
+fuzz_json_fuzzer_LDFLAGS = $(FUZZING_LIBS)
+fuzz_json_fuzzer_LDADD = $(LDADD) $(tmux_OBJECTS)
 endif
 
 # Install tmux.1 in the right format.

cmd-attach-session.c

@@ -91,8 +91,10 @@ cmd_attach_session(struct cmdq_item *item, const char *tflag, int dflag,
 	wp = target.wp;
 
 	if (wl != NULL) {
-		if (wp != NULL)
+		if (wp != NULL) {
+			window_redraw_active_switch(wp->window, wp);
 			window_set_active_pane(wp->window, wp, 1);
+		}
 		session_set_current(s, wl);
 		if (wp != NULL)
 			cmd_find_from_winlink_pane(current, wl, wp, 0);

cmd-display-menu.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: cmd-display-menu.c,v 1.54 2026/09/21 10:22:31 nicm Exp $ */
+/* $OpenBSD: cmd-display-menu.c,v 1.55 2026/09/21 12:14:32 nicm Exp $ */
 
 /*
  * Copyright (c) 2019 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -285,8 +285,8 @@ cmd_display_menu_exec(struct cmd *self, struct cmdq_item *item)
 	enum box_lines		 lines = BOX_LINES_DEFAULT;
 	char			*title, *cause = NULL;
 	int			 flags = 0, starting_choice = 0;
-	u_int			 px, py, i, count = args_count(args);
-	struct options		*o = target->s->curw->window->options;
+	u_int			 px, py, sx, sy, i, count = args_count(args);
+	struct options		*o = target->w->options;
 	struct options_entry	*oe;
 
 	if (args_has(args, 'C')) {
@@ -334,9 +334,6 @@ cmd_display_menu_exec(struct cmd *self, struct cmdq_item *item)
 	}
 	if (menu->count == 0)
 		goto out;
-	if (!cmd_display_menu_get_menu_pos(tc, item, args, &px, &py,
-	    menu->width + 4, menu->count + 2))
-		goto out;
 
 	value = args_get(args, 'b');
 	if (value != NULL) {
@@ -347,7 +344,11 @@ cmd_display_menu_exec(struct cmd *self, struct cmdq_item *item)
 			cmdq_error(item, "menu-border-lines %s", cause);
 			goto fail;
 		}
-	}
+	} else
+		lines = options_get_number(o, "menu-border-lines");
+	menu_get_size(menu, lines, &sx, &sy);
+	if (!cmd_display_menu_get_menu_pos(tc, item, args, &px, &py, sx, sy))
+		goto out;
 
 	if (args_has(args, 'O'))
 		flags |= MENU_STAYOPEN;

cmd-join-pane.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: cmd-join-pane.c,v 1.74 2026/08/03 20:29:52 nicm Exp $ */
+/* $OpenBSD: cmd-join-pane.c,v 1.75 2026/09/21 10:33:16 nicm Exp $ */
 
 /*
  * Copyright (c) 2011 George Nachman <tmux@georgester.com>
@@ -133,7 +133,7 @@ cmd_join_pane_place(struct cmdq_item *item, struct winlink *wl,
 	} else if (strcmp(position, "back") == 0) {
 		TAILQ_REMOVE(&w->z_index, wp, zentry);
 		TAILQ_FOREACH(owp, &w->z_index, zentry) {
-			if (!window_pane_is_floating(owp))
+			if (!window_pane_is_floating_with_hidden(owp))
 				break;
 		}
 		if (owp != NULL)
@@ -142,24 +142,30 @@ cmd_join_pane_place(struct cmdq_item *item, struct winlink *wl,
 			TAILQ_INSERT_TAIL(&w->z_index, wp, zentry);
 	} else if (strcmp(position, "forward") == 0) {
 		owp = TAILQ_PREV(wp, window_panes_zindex, zentry);
+		while (owp != NULL && owp->layout_cell == NULL)
+			owp = TAILQ_PREV(owp, window_panes_zindex, zentry);
 		if (owp != NULL) {
 			TAILQ_REMOVE(&w->z_index, wp, zentry);
 			TAILQ_INSERT_BEFORE(owp, wp, zentry);
 		}
 	} else if (strcmp(position, "backward") == 0) {
 		owp = TAILQ_NEXT(wp, zentry);
+		while (owp != NULL && owp->layout_cell == NULL)
+			owp = TAILQ_NEXT(owp, zentry);
 		if (owp != NULL && window_pane_is_floating(owp)) {
 			TAILQ_REMOVE(&w->z_index, wp, zentry);
 			TAILQ_INSERT_AFTER(&w->z_index, owp, wp, zentry);
 		}
 	} else if (strcmp(position, "forward-loop") == 0) {
 		owp = TAILQ_PREV(wp, window_panes_zindex, zentry);
+		while (owp != NULL && owp->layout_cell == NULL)
+			owp = TAILQ_PREV(owp, window_panes_zindex, zentry);
 		TAILQ_REMOVE(&w->z_index, wp, zentry);
 		if (owp != NULL)
 			TAILQ_INSERT_BEFORE(owp, wp, zentry);
 		else {
 			TAILQ_FOREACH(owp, &w->z_index, zentry) {
-				if (!window_pane_is_floating(owp))
+				if (!window_pane_is_floating_with_hidden(owp))
 					break;
 			}
 			if (owp != NULL)
@@ -169,6 +175,8 @@ cmd_join_pane_place(struct cmdq_item *item, struct winlink *wl,
 		}
 	} else if (strcmp(position, "backward-loop") == 0) {
 		owp = TAILQ_NEXT(wp, zentry);
+		while (owp != NULL && owp->layout_cell == NULL)
+			owp = TAILQ_NEXT(owp, zentry);
 		if (owp != NULL && window_pane_is_floating(owp)) {
 			TAILQ_REMOVE(&w->z_index, wp, zentry);
 			TAILQ_INSERT_AFTER(&w->z_index, owp, wp, zentry);
@@ -299,7 +307,7 @@ cmd_join_pane_mouse_move(struct client *c, struct mouse_event *m)
 	struct window		*w;
 	struct window_pane	*wp;
 	struct layout_cell	*lc;
-	int			 y, ly, x, lx;
+	int			 y, ly, x, lx, oxoff, oyoff, osx, osy;
 
 	wp = cmd_mouse_pane(m, NULL, &wl);
 	if (wp == NULL) {
@@ -321,10 +329,16 @@ cmd_join_pane_mouse_move(struct client *c, struct mouse_event *m)
 		ly = m->statusat - 1;
 
 	if (x != lx || y != ly) {
+		oxoff = wp->xoff;
+		oyoff = wp->yoff;
+		osx = wp->sx;
+		osy = wp->sy;
+
 		lc->g.xoff += x - lx;
 		lc->g.yoff += y - ly;
 		layout_fix_panes(w, NULL);
-		server_redraw_window(w);
+
+		window_redraw_floating_pane(wp, oxoff, oyoff, osx, osy);
 		server_redraw_window_borders(w);
 	}
 }
@@ -347,8 +361,10 @@ cmd_join_pane_zindex(struct cmdq_item *item, struct winlink *wl,
 
 	n = 0;
 	TAILQ_FOREACH(owp, &w->z_index, zentry) {
-		if (!window_pane_is_floating(owp))
+		if (!window_pane_is_floating_with_hidden(owp))
 			break;
+		if (owp->layout_cell == NULL)
+			continue;
 		if (n >= z)
 			break;
 		n++;
@@ -443,7 +459,6 @@ cmd_join_pane_exec(struct cmd *self, struct cmdq_item *item)
 				cmdq_error(item, "pane is not floating");
 				return (CMD_RETURN_ERROR);
 			}
-			server_unzoom_window(dst_w);
 			if ((s = args_get(args, 'P')) != NULL)
 				return (cmd_join_pane_place(item, dst_wl, dst_wp, s));
 			if ((s = args_get(args, 'z')) != NULL)

cmd-queue.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: cmd-queue.c,v 1.123 2026/08/24 20:34:26 nicm Exp $ */
+/* $OpenBSD: cmd-queue.c,v 1.124 2026/09/22 06:46:50 nicm Exp $ */
 
 /*
  * Copyright (c) 2013 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -580,6 +580,9 @@ cmdq_fire_command(struct cmdq_item *item)
 	int			 flags, quiet = 0;
 	char			*tmp;
 
+	if (item->client != NULL && (item->client->flags & CLIENT_DEAD))
+		return (CMD_RETURN_ERROR);
+
 	if (cfg_finished)
 		cmdq_add_message(item);
 	if (log_get_level() > 1) {

cmd-resize-pane.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: cmd-resize-pane.c,v 1.68 2026/08/31 07:44:39 nicm Exp $ */
+/* $OpenBSD: cmd-resize-pane.c,v 1.69 2026/09/21 10:33:16 nicm Exp $ */
 
 /*
  * Copyright (c) 2009 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -91,7 +91,8 @@ cmd_resize_pane_exec(struct cmd *self, struct cmdq_item *item)
 		server_redraw_window(w);
 		return (CMD_RETURN_NORMAL);
 	}
-	server_unzoom_window(w);
+	if (!window_pane_is_floating(wp))
+		server_unzoom_window(w);
 	lc = wp->layout_cell; /* may have been replaced by unzoom */
 
 	if (args_has(args, 'x')) {
@@ -236,8 +237,8 @@ cmd_resize_pane_mouse_resize_move_floating(struct client *c,
 	struct window_pane	*wp;
 	struct layout_cell	*lc;
 	int			 y, ly, x, lx, sx, sy, new_sx, new_sy;
-	int			 left, right;
-	int			 new_xoff, new_yoff, resizes = 0;
+	int			 left, right, resizes = 0;
+	int			 new_xoff, new_yoff, old_xoff, old_yoff;
 
 	wp = cmd_mouse_pane(m, NULL, &wl);
 	if (wp == NULL) {
@@ -248,6 +249,8 @@ cmd_resize_pane_mouse_resize_move_floating(struct client *c,
 	lc = wp->layout_cell;
 	sx = wp->sx;
 	sy = wp->sy;
+	old_xoff = wp->xoff;
+	old_yoff = wp->yoff;
 	left = wp->xoff - 1;
 	right = wp->xoff + sx;
 	if (window_pane_scrollbar_reserve(wp) &&
@@ -347,7 +350,7 @@ cmd_resize_pane_mouse_resize_move_floating(struct client *c,
 	}
 	if (resizes != 0) {
 		layout_fix_panes(w, NULL);
-		server_redraw_window(w);
+		window_redraw_floating_pane(wp, old_xoff, old_yoff, sx, sy);
 		server_redraw_window_borders(w);
 	}
 }

cmd-split-window.c

@@ -362,6 +362,7 @@ cmd_split_window_mouse_resize(struct client *c, struct mouse_event *m)
 	enum pane_lines		 lines;
 	u_int			 sx, sy;
 	int			 x, y, xoff, yoff, border;
+	int			 oxoff, oyoff, osx, osy;
 
 	if (c->tty.mouse_last_pane == -1)
 		return;
@@ -417,8 +418,14 @@ cmd_split_window_mouse_resize(struct client *c, struct mouse_event *m)
 	if (sy < PANE_MINIMUM)
 		sy = PANE_MINIMUM;
 
+	oxoff = wp->xoff;
+	oyoff = wp->yoff;
+	osx = wp->sx;
+	osy = wp->sy;
+
 	layout_set_size(lc, sx, sy, xoff, yoff);
 	layout_fix_panes(w, NULL);
-	server_redraw_window(w);
+
+	window_redraw_floating_pane(wp, oxoff, oyoff, osx, osy);
 	server_redraw_window_borders(w);
 }

cmd-wait-for.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: cmd-wait-for.c,v 1.23 2026/07/10 13:38:45 nicm Exp $ */
+/* $OpenBSD: cmd-wait-for.c,v 1.24 2026/09/22 06:46:50 nicm Exp $ */
 
 /*
  * Copyright (c) 2013 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -480,6 +480,40 @@ cmd_wait_for_unlock(struct cmdq_item *item, const char *name,
 	return (CMD_RETURN_NORMAL);
 }
 
+void
+cmd_wait_for_client_lost(struct client *c)
+{
+	struct wait_channel	*wc, *wc1;
+	struct wait_item	*wi, *wi1;
+	struct wait_event_item	*wei, *wei1;
+
+	TAILQ_FOREACH_SAFE(wei, &wait_event_items, entry, wei1) {
+		if (cmdq_get_client(wei->item) == c) {
+			TAILQ_REMOVE(&wait_event_items, wei, entry);
+			cmdq_continue(wei->item);
+			cmd_wait_for_event_free(wei);
+		}
+	}
+
+	RB_FOREACH_SAFE(wc, wait_channels, &wait_channels, wc1) {
+		TAILQ_FOREACH_SAFE(wi, &wc->waiters, entry, wi1) {
+			if (cmdq_get_client(wi->item) == c) {
+				cmdq_continue(wi->item);
+				TAILQ_REMOVE(&wc->waiters, wi, entry);
+				free(wi);
+			}
+		}
+		TAILQ_FOREACH_SAFE(wi, &wc->lockers, entry, wi1) {
+			if (cmdq_get_client(wi->item) == c) {
+				cmdq_continue(wi->item);
+				TAILQ_REMOVE(&wc->lockers, wi, entry);
+				free(wi);
+			}
+		}
+		cmd_wait_for_remove_empty(wc);
+	}
+}
+
 void
 cmd_wait_for_flush(void)
 {

configure.ac

@@ -111,6 +111,17 @@ case "x$DEFAULT_TERM" in
 	;;
 esac
 
+# Allow the socket directory list to be set. It is a colon-separated list of
+# directories, tried in order; a leading $ is an environment variable.
+AC_ARG_WITH(
+	socket-path,
+	AS_HELP_STRING(--with-socket-path=PATHS, set socket directory list),
+	[TMUX_SOCK=`echo "$withval" | sed 's/[[$]]/$$/g'`],
+	[TMUX_SOCK=]
+)
+AM_CONDITIONAL(HAVE_TMUX_SOCK, [test "x$TMUX_SOCK" != x])
+AC_SUBST(TMUX_SOCK)
+
 # Do we need fuzzers?
 AM_CONDITIONAL(NEED_FUZZING, test "x$enable_fuzzing" = xyes)
 

fuzz/input-fuzzer.c

@@ -44,7 +44,7 @@ LLVMFuzzerTestOneInput(const u_char *data, size_t size)
 	w = window_create(PANE_WIDTH, PANE_HEIGHT, 0, 0);
 	wp = window_add_pane(w, NULL, 0, 0);
 	bufferevent_pair_new(libevent, BEV_OPT_CLOSE_ON_FREE, vpty);
-	wp->ictx = input_init(wp, vpty[0], NULL, NULL);
+	wp->ictx = input_init(wp, vpty[0], NULL);
 	window_add_ref(w, __func__);
 
 	wp->fd = open("/dev/null", O_WRONLY);

fuzz/json-fuzzer.c

@@ -0,0 +1,88 @@
+/*
+ * Fuzz the tmux JSON parser and serializer.
+ */
+
+#include <stdint.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "tmux.h"
+
+struct event_base *libevent;
+
+static void
+walk_json(struct json_node *node)
+{
+	struct json_node	*child, *object;
+	const char		*string;
+	int64_t		 number;
+	int		 boolean;
+
+	if (node == NULL)
+		return;
+
+	(void)json_get_string(node, &string);
+	(void)json_get_number(node, &number);
+	(void)json_get_boolean(node, &boolean);
+
+	if (json_get_object(node, &object) == 0) {
+		(void)json_find(object, "V");
+		(void)json_find(object, "L");
+	}
+
+	for (child = json_array_first(node); child != NULL;
+	    child = json_array_next(child))
+		walk_json(child);
+}
+
+int
+LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
+{
+	struct json_node	*node;
+	char			*input, *serialized, *cause = NULL;
+
+	if (size == 0 || size > 1U << 20)
+		return 0;
+
+	input = malloc(size + 1);
+	if (input == NULL)
+		return 0;
+	memcpy(input, data, size);
+	input[size] = '\0';
+
+	node = json_parse(input, &cause);
+	free(cause);
+	if (node != NULL) {
+		walk_json(node);
+		serialized = json_to_string(node);
+		free(serialized);
+		json_destroy_node(node);
+	}
+
+	free(input);
+	return 0;
+}
+
+int
+LLVMFuzzerInitialize(__unused int *argc, __unused char ***argv)
+{
+	const struct options_table_entry	*oe;
+
+	global_environ = environ_create();
+	global_options = options_create(NULL);
+	global_s_options = options_create(NULL);
+	global_w_options = options_create(NULL);
+	for (oe = options_table; oe->name != NULL; oe++) {
+		if (oe->scope & OPTIONS_TABLE_SERVER)
+			options_default(global_options, oe);
+		if (oe->scope & OPTIONS_TABLE_SESSION)
+			options_default(global_s_options, oe);
+		if (oe->scope & OPTIONS_TABLE_WINDOW)
+			options_default(global_w_options, oe);
+	}
+	libevent = osdep_event_init();
+	socket_path = xstrdup("dummy");
+
+	return 0;
+}

fuzz/json-fuzzer.dict

@@ -0,0 +1,37 @@
+# JSON structural tokens
+"{"
+"}"
+"["
+"]"
+":"
+","
+"\""
+
+# JSON values
+"true"
+"false"
+"null"
+"0"
+"-1"
+"123456789"
+"\\\""
+"\\\\"
+"\\n"
+"\\u0000"
+
+# tmux layout/control-mode keys
+"V"
+"L"
+"W"
+"H"
+"X"
+"Y"
+"T"
+"S"
+"id"
+"result"
+"error"
+"routes"
+"uri"
+"name"
+"value"

fuzz/json-fuzzer.options

@@ -0,0 +1,2 @@
+[libfuzzer]
+max_len = 4096

fuzz/layout-fuzzer.c

@@ -0,0 +1,111 @@
+/*
+ * Copyright (c) 2026 Arthur Chan <arthur.chan@adalogics.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
+ * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
+ * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * Fuzz the custom layout parser.
+ *
+ * A layout string such as "bb62,80x24,0,0{40x24,0,0,1,39x24,41,0,2}" is
+ * accepted by select-layout and is what tmux stores and restores for a
+ * window, so it is parsed from configuration and from commands. It drives
+ * layout-custom.c (the string parser and the checksum), then layout.c, which
+ * resizes and assigns the cells.
+ *
+ * layout_parse() refuses a window with no panes, and refuses a layout whose
+ * cell count is smaller than the pane count, so the window is given a fixed
+ * number of panes. The count is fixed rather than derived from the input, so
+ * a mutation always means a different layout string.
+ */
+
+#include <sys/types.h>
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "tmux.h"
+
+#define FUZZER_MAXLEN 1024
+#define FUZZER_PANES 4
+
+struct event_base	*libevent;
+
+int
+LLVMFuzzerTestOneInput(const u_char *data, size_t size)
+{
+	struct window		*w;
+	struct window_pane	*wp;
+	char			*buf, *cause = NULL, *dump;
+	u_int			 i;
+
+	if (size == 0 || size > FUZZER_MAXLEN)
+		return 0;
+
+	/* layout_parse() takes a C string. */
+	buf = malloc(size + 1);
+	if (buf == NULL)
+		return 0;
+	memcpy(buf, data, size);
+	buf[size] = '\0';
+
+	w = window_create(80, 24, 0, 0);
+	if (w == NULL) {
+		free(buf);
+		return 0;
+	}
+	window_add_ref(w, __func__);
+
+	for (i = 0; i < FUZZER_PANES; i++) {
+		wp = window_add_pane(w, NULL, 0, 0);
+		if (w->active == NULL)
+			w->active = wp;
+	}
+
+	if (layout_parse(w, buf, &cause) == 0) {
+		dump = layout_dump(w, w->layout_root, 1);
+		free(dump);
+	}
+	free(cause);
+
+	window_remove_ref(w, __func__);
+
+	free(buf);
+	return 0;
+}
+
+int
+LLVMFuzzerInitialize(__unused int *argc, __unused char ***argv)
+{
+	const struct options_table_entry	*oe;
+
+	global_environ = environ_create();
+	global_options = options_create(NULL);
+	global_s_options = options_create(NULL);
+	global_w_options = options_create(NULL);
+	for (oe = options_table; oe->name != NULL; oe++) {
+		if (oe->scope & OPTIONS_TABLE_SERVER)
+			options_default(global_options, oe);
+		if (oe->scope & OPTIONS_TABLE_SESSION)
+			options_default(global_s_options, oe);
+		if (oe->scope & OPTIONS_TABLE_WINDOW)
+			options_default(global_w_options, oe);
+	}
+
+	libevent = osdep_event_init();
+
+	socket_path = xstrdup("dummy");
+
+	return 0;
+}

fuzz/layout-fuzzer.dict

@@ -0,0 +1,17 @@
+# tmux custom layout strings: "<checksum>,<sx>x<sy>,<x>,<y>{...}" / "[...]"
+","
+"x"
+"{"
+"}"
+"["
+"]"
+"0"
+"1"
+"80x24,0,0"
+"40x24,0,0"
+"bb62,"
+"cafe,"
+",0,0,0"
+",0,0{"
+",0,0["
+"@"

fuzz/layout-fuzzer.options

@@ -0,0 +1,2 @@
+[libfuzzer]
+max_len = 1024

key-bindings.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: key-bindings.c,v 1.192 2026/08/06 09:05:04 nicm Exp $ */
+/* $OpenBSD: key-bindings.c,v 1.193 2026/09/21 20:45:48 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -523,7 +523,7 @@ key_bindings_init(void)
 		"bind -n TripleClick1Pane { select-pane -t=; if -F '#{||:#{pane_in_mode},#{mouse_any_flag}}' { send -M } { copy-mode -H; send -X select-line; run -d0.3; send -X copy-pipe-and-cancel } }",
 
 		/* Mouse button 1 on border. */
-		"bind -n MouseDown1Border { select-pane -M }",
+		"bind -n MouseDown1Border { select-pane -t= }",
 
 		/* Mouse button 1 drag on border. */
 		"bind -n MouseDrag1Border { resize-pane -M }",

layout-custom.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: layout-custom.c,v 1.42 2026/09/20 08:37:47 nicm Exp $ */
+/* $OpenBSD: layout-custom.c,v 1.43 2026/09/22 06:48:01 nicm Exp $ */
 
 /*
  * Copyright (c) 2010 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -307,6 +307,37 @@ bad:
 	return (xstrdup("0000,"));
 }
 
+/* Get a floating pane cell's z-index in the layout being dumped. */
+static u_int
+layout_cell_zindex(struct layout_cell *lc)
+{
+	struct window_pane	*wp = lc->wp, *wq;
+	struct window		*w = wp->window;
+	struct layout_cell	*other;
+	int			 saved = (lc == wp->saved_layout_cell);
+	u_int			 i = 0;
+
+	if (saved &&
+	    w->active != NULL &&
+	    (w->active->flags & PANE_ZOOMED) &&
+	    (w->active->saved_layout_cell->flags & LAYOUT_CELL_FLOATING)) {
+		if (wp == w->active)
+			return (0);
+		i++;
+	}
+	TAILQ_FOREACH(wq, &w->z_index, zentry) {
+		if (wq == wp)
+			break;
+		if (saved)
+			other = wq->saved_layout_cell;
+		else
+			other = wq->layout_cell;
+		if (other != NULL && (other->flags & LAYOUT_CELL_FLOATING))
+			i++;
+	}
+	return (i);
+}
+
 /* Append information for a single cell in a JSON (v2) format. */
 static int
 layout_append_v2(struct layout_cell *lc, struct layout_string *ls)
@@ -315,7 +346,7 @@ layout_append_v2(struct layout_cell *lc, struct layout_string *ls)
 	struct window_pane	*wp;
 	enum layout_type	 type;
 	char			 c;
-	u_int			 i, n;
+	u_int			 i, n, z;
 
 	if (lc == NULL)
 		return (-1);
@@ -356,9 +387,10 @@ layout_append_v2(struct layout_cell *lc, struct layout_string *ls)
 		if (window_pane_index(wp, &i) != 0)
 			return (-1);
 		layout_string_write(ls, ",\"i\":%u", i);
-		if ((lc->flags & LAYOUT_CELL_FLOATING) &&
-		    window_pane_zindex(wp, &i) == 0)
-			layout_string_write(ls, ",\"z\":%u", i);
+		if (lc->flags & LAYOUT_CELL_FLOATING) {
+			z = layout_cell_zindex(lc);
+			layout_string_write(ls, ",\"z\":%u", z);
+		}
 		layout_string_write(ls, ",\"I\":\"%%%u\"", wp->id);
 	}
 

layout.c

@@ -469,7 +469,6 @@ layout_fix_panes(struct window *w, struct window_pane *skip)
 					sx = PANE_MINIMUM;
 				else
 					sx = sx - sb_w - sb_pad;
-			wp->flags |= PANE_REDRAWSCROLLBAR;
 		}
 
 		window_pane_resize(wp, sx, sy);
@@ -477,8 +476,11 @@ layout_fix_panes(struct window *w, struct window_pane *skip)
 		if (wp->xoff != old_xoff ||
 		    wp->yoff != old_yoff ||
 		    wp->sx != old_sx ||
-		    wp->sy != old_sy)
+		    wp->sy != old_sy) {
+			if (window_pane_scrollbar_reserve(wp))
+				wp->flags |= PANE_REDRAWSCROLLBAR;
 			changed = 1;
+		}
 	}
 	if (changed)
 		redraw_invalidate_scene(w);

menu.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: menu.c,v 1.70 2026/08/17 07:33:55 nicm Exp $ */
+/* $OpenBSD: menu.c,v 1.71 2026/09/21 12:14:32 nicm Exp $ */
 
 /*
  * Copyright (c) 2019 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -51,6 +51,18 @@ struct menu_data {
 	void			*data;
 };
 
+void
+menu_get_size(struct menu *menu, enum box_lines lines, u_int *sx, u_int *sy)
+{
+	if (lines == BOX_LINES_NONE) {
+		*sx = menu->item_width + 2;
+		*sy = menu->count;
+	} else {
+		*sx = menu->width + 4;
+		*sy = menu->count + 2;
+	}
+}
+
 void
 menu_add_items(struct menu *menu, const struct menu_item *items,
     struct cmdq_item *qitem, struct client *c, struct cmd_find_state *fs)
@@ -142,6 +154,8 @@ menu_add_item(struct menu *menu, const struct menu_item *item,
 	width = format_width(new_item->name);
 	if (*new_item->name == '-')
 		width--;
+	if (width > menu->item_width)
+		menu->item_width = width;
 	if (width > menu->width)
 		menu->width = width;
 }
@@ -238,7 +252,7 @@ menu_update(struct menu_data *md)
 	screen_write_clearscreen(&ctx, 8);
 
 	if (md->border_lines != BOX_LINES_NONE) {
-		screen_write_box(&ctx, menu->width + 4, menu->count + 2,
+		screen_write_box(&ctx, menu_width(md), menu_height(md),
 		    md->border_lines, &md->border_style_gc, menu->title);
 	}
 
@@ -286,11 +300,13 @@ menu_destroy(struct window *w)
 void
 menu_get_cursor(struct menu_data *md, u_int *cx, u_int *cy)
 {
-	*cx = md->px + 2;
+	u_int	border = (md->border_lines != BOX_LINES_NONE);
+
+	*cx = md->px + 1 + border;
 	if (md->choice == -1)
 		*cy = md->py;
 	else
-		*cy = md->py + 1 + md->choice;
+		*cy = md->py + border + md->choice;
 }
 
 struct screen *
@@ -302,13 +318,19 @@ menu_screen(struct menu_data *md)
 u_int
 menu_width(struct menu_data *md)
 {
-	return (md->menu->width + 4);
+	u_int	sx, sy;
+
+	menu_get_size(md->menu, md->border_lines, &sx, &sy);
+	return (sx);
 }
 
 u_int
 menu_height(struct menu_data *md)
 {
-	return (md->menu->count + 2);
+	u_int	sx, sy;
+
+	menu_get_size(md->menu, md->border_lines, &sx, &sy);
+	return (sy);
 }
 
 u_int
@@ -338,6 +360,7 @@ menu_key(struct client *c, struct menu_data *md, struct key_event *event)
 	enum cmd_parse_status		 status;
 	char				*error;
 	key_code			 key;
+	u_int				 border;
 
 	if (KEYC_IS_MOUSE(event->key)) {
 		/*
@@ -353,10 +376,10 @@ menu_key(struct client *c, struct menu_data *md, struct key_event *event)
 				return (1);
 			return (0);
 		}
-		if (m->x < md->px ||
-		    m->x > md->px + 4 + menu->width ||
-		    m->y < md->py + 1 ||
-		    m->y > md->py + 1 + n - 1) {
+		border = (md->border_lines != BOX_LINES_NONE);
+		if (m->x < md->px || m->x >= md->px + menu_width(md) ||
+		    m->y < md->py + border ||
+		    m->y >= md->py + border + n) {
 			if (~md->flags & MENU_STAYOPEN) {
 				if (!move && MOUSE_RELEASE(m->b))
 					return (1);
@@ -379,7 +402,7 @@ menu_key(struct client *c, struct menu_data *md, struct key_event *event)
 			if (!MOUSE_WHEEL(m->b) && !MOUSE_DRAG(m->b))
 				goto chosen;
 		}
-		md->choice = m->y - (md->py + 1);
+		md->choice = m->y - (md->py + border);
 		if (md->choice != old)
 			server_redraw_window_menu(md->w);
 		return (0);
@@ -546,20 +569,16 @@ menu_resize(struct menu_data *md, struct window *w)
 
 	if (md == NULL)
 		return;
-
 	nx = md->px;
 	ny = md->py;
 
-	sx = md->menu->width + 4;
-	sy = md->menu->count + 2;
-
+	menu_get_size(md->menu, md->border_lines, &sx, &sy);
 	if (nx + sx > w->sx) {
 		if (w->sx <= sx)
 			nx = 0;
 		else
 			nx = w->sx - sx;
 	}
-
 	if (ny + sy > w->sy) {
 		if (w->sy <= sy)
 			ny = 0;
@@ -591,8 +610,9 @@ menu_display(struct menu *menu, int flags, int starting_choice,
 		w = fs->w;
 	o = w->options;
 
-	sx = menu->width + 4;
-	sy = menu->count + 2;
+	if (lines == BOX_LINES_DEFAULT)
+		lines = options_get_number(o, "menu-border-lines");
+	menu_get_size(menu, lines, &sx, &sy);
 	if (sx >= w->sx)
 		px = 0;
 	else if (px + sx > w->sx)
@@ -604,9 +624,6 @@ menu_display(struct menu *menu, int flags, int starting_choice,
 	w->menu_last_px = px;
 	w->menu_last_py = py;
 
-	if (lines == BOX_LINES_DEFAULT)
-		lines = options_get_number(o, "menu-border-lines");
-
 	md = xcalloc(1, sizeof *md);
 	md->w = w;
 	md->flags = flags;

mode-tree.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: mode-tree.c,v 1.101 2026/08/05 07:50:21 nicm Exp $ */
+/* $OpenBSD: mode-tree.c,v 1.103 2026/09/24 18:59:00 nicm Exp $ */
 
 /*
  * Copyright (c) 2017 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -277,11 +277,22 @@ mode_tree_free_items(struct mode_tree_list *mtl)
 static void
 mode_tree_check_selected(struct mode_tree_data *mtd)
 {
+	if (mtd->height == 0)
+		return;
+
+	/* If the list has shrunk, do not leave empty lines at the bottom. */
+	if (mtd->line_size <= mtd->height)
+		mtd->offset = 0;
+	else if (mtd->offset > mtd->line_size - mtd->height)
+		mtd->offset = mtd->line_size - mtd->height;
+
 	/*
-	 * If the current line would now be off screen reset the offset to the
-	 * last visible line.
+	 * If the current line would now be off screen move the offset so it is
+	 * visible.
 	 */
-	if (mtd->current > mtd->height - 1)
+	if (mtd->current < mtd->offset)
+		mtd->offset = mtd->current;
+	else if (mtd->current > mtd->offset + mtd->height - 1)
 		mtd->offset = mtd->current - mtd->height + 1;
 }
 
@@ -501,20 +512,14 @@ mode_tree_set_current(struct mode_tree_data *mtd, uint64_t tag)
 
 	if (mode_tree_get_tag(mtd, tag, &found)) {
 		mtd->current = found;
-		if (mtd->current > mtd->height - 1)
-			mtd->offset = mtd->current - mtd->height + 1;
-		else
-			mtd->offset = 0;
+		mode_tree_check_selected(mtd);
 		return (1);
 	}
 	if (mtd->current >= mtd->line_size) {
 		if (mtd->line_size == 0)
 			return (0);
 		mtd->current = mtd->line_size - 1;
-		if (mtd->current > mtd->height - 1)
-			mtd->offset = mtd->current - mtd->height + 1;
-		else
-			mtd->offset = 0;
+		mode_tree_check_selected(mtd);
 	}
 	return (0);
 }
@@ -683,13 +688,13 @@ mode_tree_build(struct mode_tree_data *mtd)
 
 	if (mtd->line_list != NULL && tag == UINT64_MAX)
 		tag = mtd->line_list[mtd->current].item->tag;
-	mode_tree_set_current(mtd, tag);
 
 	mtd->width = screen_size_x(s);
 	if (mtd->preview != MODE_TREE_PREVIEW_OFF)
 		mode_tree_set_height(mtd);
 	else
 		mtd->height = screen_size_y(s);
+	mode_tree_set_current(mtd, tag);
 	mode_tree_check_selected(mtd);
 }
 
@@ -1375,12 +1380,14 @@ static void
 mode_tree_display_menu(struct mode_tree_data *mtd, struct client *c, u_int x,
     u_int y, int outside)
 {
+	struct window		*w = mtd->wp->window;
 	struct mode_tree_item	*mti;
 	struct menu		*menu;
 	const struct menu_item	*items;
 	struct mode_tree_menu	*mtm;
 	char			*title;
-	u_int			 line;
+	enum box_lines		 lines;
+	u_int			 line, sx, sy;
 
 	if (mtd->offset + y > mtd->line_size - 1)
 		line = mtd->current;
@@ -1405,14 +1412,17 @@ mode_tree_display_menu(struct mode_tree_data *mtd, struct client *c, u_int x,
 	mtm->line = line;
 	mtd->references++;
 
-	if (x >= (menu->width + 4) / 2)
-		x -= (menu->width + 4) / 2;
+	lines = options_get_number(w->options, "menu-border-lines");
+	menu_get_size(menu, lines, &sx, &sy);
+	if (x >= sx / 2)
+		x -= sx / 2;
 	else
 		x = 0;
 	x += mtd->wp->xoff;
 	y += mtd->wp->yoff;
-	if (menu_display(menu, 0, 0, NULL, x, y, c, BOX_LINES_DEFAULT, NULL,
-	    NULL, NULL, NULL, mode_tree_menu_callback, mtm) != 0) {
+
+	if (menu_display(menu, 0, 0, NULL, x, y, c, lines, NULL, NULL, NULL,
+	    NULL, mode_tree_menu_callback, mtm) != 0) {
 		mode_tree_remove_ref(mtd);
 		free(mtm);
 		menu_free(menu);

regress/Makefile

@@ -1,33 +1,17 @@
 TESTS!= echo *.sh
 LOGDIR=logs
 
-.PHONY: all
-.NOTPARALLEL: all
+.PHONY: all prepare $(TESTS)
 
-all:
-	@mkdir -p "$(LOGDIR)"; \
-	rm -f "$(LOGDIR)"/*.log; \
-	failed=0; failures=; \
+all: prepare $(TESTS)
+	@failed=0; failures=; \
 	for test in $(TESTS); do \
 		base=$${test##*/}; \
 		log="$(LOGDIR)/$${base%.sh}.log"; \
-		rm -f "$$log"; \
-		printf '%-40s ' "$$test"; \
-		start=$$(date +%s); \
-		env -i LC_CTYPE=C.UTF-8 MallocNanoZone=0 \
-		    sh -x "$$test" >"$$log" 2>&1; \
-		if [ $$? -eq 0 ]; then \
-			end=$$(date +%s); \
-			rm -f "$$log"; \
-			echo "PASS ($$((end - start))s)"; \
-		else \
-			end=$$(date +%s); \
-			echo "FAIL ($$((end - start))s)"; \
-			echo " log: $$log"; \
+		if [ -f "$$log" ]; then \
 			failed=1; \
 			failures="$$failures $$test"; \
 		fi; \
-		sleep 1; \
 	done; \
 	if [ "$$failed" -ne 0 ]; then \
 		echo; \
@@ -39,3 +23,22 @@ all:
 		rmdir "$(LOGDIR)" 2>/dev/null || true; \
 	fi; \
 	exit $$failed
+
+prepare:
+	@mkdir -p "$(LOGDIR)"
+	@rm -f "$(LOGDIR)"/*.log
+
+$(TESTS): prepare
+	@base="$@"; base=$${base##*/}; \
+	log="$(LOGDIR)/$${base%.sh}.log"; \
+	start=$$(date +%s); \
+	if env -i LC_CTYPE=C.UTF-8 MallocNanoZone=0 \
+	    sh -x "$@" >"$$log" 2>&1; then \
+		end=$$(date +%s); \
+		rm -f "$$log"; \
+		printf '%-40s PASS (%ss)\n' "$@" "$$((end - start))"; \
+	else \
+		end=$$(date +%s); \
+		printf '%-40s FAIL (%ss)\n log: %s\n' \
+		    "$@" "$$((end - start))" "$$log"; \
+	fi

regress/attach-session-redraw.sh

@@ -0,0 +1,79 @@
+#!/bin/sh
+
+# Selecting a pane with attach-session from an already attached client must
+# redraw pane contents when window-style and window-active-style differ.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+INNER="$TEST_TMUX -Lattach-redraw-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Lattach-redraw-outer-$$ -f/dev/null"
+BEFORE=$DIR/before
+AFTER=$DIR/after
+
+fail()
+{
+	echo "$*" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+wait_for_client()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		CLIENT=$($INNER list-clients -F '#{client_name}' 2>/dev/null)
+		[ -n "$CLIENT" ] && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "inner client did not attach"
+}
+
+LEFT=$($INNER new-session -dPF '#{pane_id}' -s inner -x 40 -y 8 \
+    "printf 'LEFT'; exec sleep 100") || exit 1
+$INNER set-option -g status off || exit 1
+$INNER set-option -g window-size manual || exit 1
+$INNER set-option -g default-terminal screen || exit 1
+$INNER split-window -h -t "$LEFT" "printf 'RIGHT'; exec sleep 100" || exit 1
+$INNER set-option -w -t "$LEFT" window-style bg=red || exit 1
+$INNER set-option -w -t "$LEFT" window-active-style bg=blue || exit 1
+$INNER bind-key -n x attach-session -t "$LEFT" || exit 1
+
+$OUTER new-session -d -s outer -x 40 -y 8 'sleep 100' || exit 1
+$OUTER set-option -g status off || exit 1
+$OUTER set-option -g window-size manual || exit 1
+$OUTER set-option -g default-terminal screen || exit 1
+$OUTER respawn-pane -k -t outer:0.0 \
+    "$TEST_TMUX -Lattach-redraw-inner-$$ -f/dev/null attach-session -t inner" ||
+    exit 1
+
+wait_for_client
+sleep 1
+$OUTER send-keys -t outer:0.0 x || exit 1
+sleep 1
+[ "$($INNER display-message -p -t inner '#{pane_id}')" = "$LEFT" ] ||
+    fail "attach-session did not select the target pane"
+$OUTER capture-pane -pe -t outer:0.0 >"$BEFORE" || exit 1
+
+# A forced redraw produces the correct scene. It must be identical to the
+# scene drawn immediately by attach-session.
+$INNER refresh-client -t "$CLIENT" || exit 1
+sleep 1
+$OUTER capture-pane -pe -t outer:0.0 >"$AFTER" || exit 1
+cmp -s "$BEFORE" "$AFTER" ||
+    fail "attach-session left stale active/inactive pane styles"
+
+exit 0

regress/check-names.sh

@@ -5,6 +5,15 @@
 PATH=/bin:/usr/bin
 TERM=screen
 
+# The pane's shell must not be the user's own interactive shell: a custom
+# PS1/PROMPT_COMMAND that sets the terminal title (as many do, for tmux/xterm
+# TERM types) would redraw over the titles this test sets and checks on
+# every prompt, regardless of how long it waits first.
+shell=
+if command -v bash >/dev/null 2>&1; then
+	shell='bash --noprofile --norc +o history'
+fi
+
 [ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
 TMUX="$TEST_TMUX -LtestA$$ -f/dev/null"
 $TMUX kill-server 2>/dev/null
@@ -30,7 +39,7 @@ must_equal()
 	[ "$got" = "$want" ] || fail "got '$got', expected '$want'"
 }
 
-$TMUX new-session -d -x 80 -y 24 || exit 1
+$TMUX new-session -d -x 80 -y 24 -- $shell || exit 1
 $TMUX set-option -qg allow-set-title on || exit 1
 $TMUX set-option -qg allow-rename on || exit 1
 $TMUX set-option -qg automatic-rename off || exit 1

regress/control-client-exit-stalled.sh

@@ -17,7 +17,7 @@ PATH=/bin:/usr/bin
 TERM=screen
 
 [ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
-TMUX="$TEST_TMUX -Ltest"
+TMUX="$TEST_TMUX -Ltest$$"
 $TMUX kill-server 2>/dev/null
 
 DIR=$(mktemp -d)

regress/control-client-exit.sh

@@ -19,7 +19,7 @@ PATH=/bin:/usr/bin
 TERM=screen
 
 [ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
-TMUX="$TEST_TMUX -Ltest"
+TMUX="$TEST_TMUX -Ltest$$"
 $TMUX kill-server 2>/dev/null
 
 DIR=$(mktemp -d)

regress/control-client-popup.sh

@@ -1,6 +1,7 @@
 #!/bin/sh
 
-# Popups require a tty overlay and cannot be displayed by a control client.
+# Popups require an attached terminal and cannot be displayed by a control
+# client.
 # A popup command from control mode must be ignored cleanly, leaving the
 # client command queue and server usable.
 

regress/control-client-run-shell-exit.sh

@@ -10,7 +10,7 @@ PATH=/bin:/usr/bin
 TERM=screen
 
 [ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
-TMUX="$TEST_TMUX -Ltest"
+TMUX="$TEST_TMUX -Ltest$$"
 $TMUX kill-server 2>/dev/null
 
 OUT=$(mktemp)

regress/control-client-wait-exit.sh

@@ -10,7 +10,7 @@ PATH=/bin:/usr/bin
 TERM=screen
 
 [ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
-TMUX="$TEST_TMUX -Ltest"
+TMUX="$TEST_TMUX -Ltest$$"
 $TMUX kill-server 2>/dev/null
 
 FIFO=$(mktemp -u)

regress/copy-mode-source-blank.sh

@@ -0,0 +1,63 @@
+#!/bin/sh
+
+# Trimming a blank source must leave a visible line for cursor reflow.
+
+PATH=/bin:/usr/bin
+TERM=screen
+export PATH TERM
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+TMUX="$TEST_TMUX -LtestA$$ -f/dev/null"
+
+fail()
+{
+	echo "$*" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$TMUX kill-server 2>/dev/null
+}
+trap cleanup 0
+trap 'exit 1' 1 2 3 15
+
+$TMUX new-session -d -x80 -y24 -s test 'sleep 100' || exit 1
+$TMUX set-option -g window-size manual || exit 1
+$TMUX new-window -t test:1 'sleep 100' || exit 1
+$TMUX resize-window -t test:0 -x20 -y24 || exit 1
+
+# Exercise widening, narrowing, and equal widths with no source history.
+for pair in '0 1' '1 0' '1 2'; do
+	set -- $pair
+	if [ "$2" = 2 ]; then
+		$TMUX new-window -t test:2 'sleep 100' || exit 1
+		$TMUX resize-window -t test:2 -x80 -y24 || exit 1
+	fi
+	source=test:$1.0
+	target=test:$2.0
+	[ "$($TMUX display-message -p -t "$source" '#{history_size}')" = 0 ] ||
+		fail "source has unexpected history"
+	$TMUX copy-mode -s "$source" -t "$target" || exit 1
+	$TMUX has-session -t test || fail "server died copying blank source"
+	[ "$($TMUX display-message -p -t "$target" \
+	    '#{pane_in_mode} #{copy_cursor_x} #{copy_cursor_y}')" = '1 0 0' ] ||
+		fail "blank source did not enter copy mode at the first cell"
+	$TMUX send-keys -t "$target" -X cancel || exit 1
+done
+
+# Real content still trims trailing empty lines, clamping the cursor to beta.
+$TMUX respawn-pane -k -t test:0.0 \
+	"printf 'alpha\r\nbeta\r\n\r\n\r\n'; exec sleep 100" || exit 1
+i=0
+while [ "$($TMUX display-message -p -t test:0.0 '#{cursor_y}')" != 4 ]; do
+	i=$((i + 1))
+	[ "$i" -lt 10 ] || fail "source output did not arrive"
+	sleep 1
+done
+$TMUX copy-mode -s test:0.0 -t test:1.0 || exit 1
+[ "$($TMUX display-message -p -t test:1.0 \
+    '#{pane_in_mode} #{copy_cursor_y} #{copy_cursor_line}')" = '1 1 beta' ] ||
+	fail "nonblank source content or trailing-line trimming changed"
+
+exit 0

regress/display-panes.sh

@@ -153,11 +153,13 @@ wait_format "$p0" '#{pane_in_mode}' '0'
 wait_option @picked "$p1"
 
 # Commands after display-panes run immediately while the mode remains.
+# Record the mode in the same command queue so client startup cannot race
+# the 500ms timeout.
 $TMUX set -g @after none || fail "set @after failed"
-$TMUX display-panes -Nd 500 -t "$p0" \; set -g @after fast ||
+$TMUX display-panes -Nd 500 -t "$p0" \; \
+    set -gF -t "$p0" @after '#{pane_mode}' ||
 	fail "display-panes immediate command failed"
-wait_option @after fast
-wait_format "$p0" '#{pane_mode}' 'panes-mode'
+wait_option @after 'panes-mode'
 wait_format "$p0" '#{pane_in_mode}' '0'
 
 # Existing zoom is restored on exit.

regress/floating-pane-border-style-cross-client.sh

@@ -0,0 +1,135 @@
+#!/bin/sh
+
+# Damage-only redraws must evaluate both active and inactive border styles
+# for each client, even though the cached border cells belong to the pane.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+INNER="$TEST_TMUX -Lborder-style-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Lborder-style-outer-$$ -f/dev/null"
+CAPTURE=$DIR/capture
+
+fail()
+{
+	echo "$*" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+wait_for_clients()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		count=$($INNER list-clients 2>/dev/null | wc -l)
+		[ "$count" -eq 2 ] && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "two inner clients did not attach"
+}
+
+wait_for_marker()
+{
+	target=$1
+	marker=$2
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t "$target" >"$CAPTURE" || exit 1
+		grep -q "$marker" "$CAPTURE" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "client in $target did not receive $marker"
+}
+
+cat >"$DIR/emitter.pl" <<'PERL'
+use strict;
+use warnings;
+
+$| = 1;
+for my $phase (1 .. 2) {
+	while (!-e "$ENV{TRIGGER}-$phase") {
+		select undef, undef, undef, 0.01;
+	}
+	# Change an unused palette entry and acknowledge it in the pane body.
+	print "\e]4;200;rgb:11/22/0$phase\a\e[1;1HDAMAGE$phase";
+}
+sleep 100;
+PERL
+
+$INNER new-session -d -s inner -x 60 -y 20 \
+    "TRIGGER='$DIR/trigger' perl '$DIR/emitter.pl'" || exit 1
+$INNER set -g status off || exit 1
+$INNER set -g window-size manual || exit 1
+$INNER set -g automatic-rename off || exit 1
+$INNER set -g status-interval 0 || exit 1
+$INNER set -g pane-border-lines simple || exit 1
+$INNER set -g pane-border-status top || exit 1
+$INNER set -g pane-border-format 'CLIENT=#{client_name}' || exit 1
+FLOAT=$($INNER new-pane -d -PF '#{pane_id}' -x 35 -y 6 -X 5 -Y 5 \
+    'sleep 100') || exit 1
+
+$OUTER new-session -d -s outer -x 121 -y 20 'sleep 100' || exit 1
+$OUTER set -g status off || exit 1
+$OUTER set -g window-size manual || exit 1
+$OUTER set -g default-terminal screen || exit 1
+LEFT=$($OUTER display-message -p -t outer:0.0 '#{pane_id}') || exit 1
+RIGHT=$($OUTER split-window -h -PF '#{pane_id}' 'sleep 100') || exit 1
+for target in "$LEFT" "$RIGHT"; do
+	$OUTER respawn-pane -k -t "$target" "$INNER attach-session -t inner" ||
+	    exit 1
+done
+wait_for_clients
+
+NAME1=$($OUTER display-message -p -t "$LEFT" '#{pane_tty}') || exit 1
+NAME2=$($OUTER display-message -p -t "$RIGHT" '#{pane_tty}') || exit 1
+STYLE="fg=#{?#{==:#{client_name},$NAME1},red,blue}"
+$INNER set -g pane-border-style "$STYLE" || exit 1
+$INNER set -g pane-active-border-style "$STYLE" || exit 1
+
+# Capture just the floating pane's rows, excluding the acknowledgement in
+# the tiled pane. Exercise each cache by changing the floating pane's focus.
+phase=1
+while [ "$phase" -le 2 ]; do
+	if [ "$phase" -eq 2 ]; then
+		$INNER select-pane -t "$FLOAT" || exit 1
+	fi
+	$INNER refresh-client -t "$NAME1" || exit 1
+	$INNER refresh-client -t "$NAME2" || exit 1
+	sleep 0.5
+	for target in "$LEFT" "$RIGHT"; do
+		$OUTER capture-pane -pe -S 5 -E 10 -t "$target" \
+		    >"$DIR/before-$target" || exit 1
+	done
+	RED=$(printf '\033[31m')
+	BLUE=$(printf '\033[34m')
+	grep -Fq "$RED" "$DIR/before-$LEFT" || fail "missing red border"
+	grep -Fq "$BLUE" "$DIR/before-$RIGHT" || fail "missing blue border"
+
+	: >"$DIR/trigger-$phase"
+	wait_for_marker "$LEFT" "DAMAGE$phase"
+	wait_for_marker "$RIGHT" "DAMAGE$phase"
+	sleep 0.2
+	for target in "$LEFT" "$RIGHT"; do
+		$OUTER capture-pane -pe -S 5 -E 10 -t "$target" \
+		    >"$CAPTURE" || exit 1
+		diff -u "$DIR/before-$target" "$CAPTURE" ||
+		    fail "phase $phase changed $target's border style"
+	done
+	phase=$((phase + 1))
+done
+
+exit 0

regress/floating-pane-drag-ghost.sh

@@ -0,0 +1,108 @@
+#!/bin/sh
+
+# Regression test for a floating-pane drag bug: cmd_resize_pane_redraw_floating()
+# (cmd-resize-pane.c) reported damage for just a dragged floating pane's
+# content rectangle, not the one-cell border frame drawn around it (see the
+# "floating" case in screen-redraw.c, which draws that frame at
+# xoff-1/yoff-1 through xoff+sx/yoff+sy - one cell outside the pane's own
+# content area). Damage scoped to only the content area left the frame's
+# previous position undrawn as the pane moved, so dragging it left a trail
+# of un-erased border frames behind - visible as several "corners" stacked
+# up rather than just the pane's current one.
+#
+# This bug has nothing to do with images - it reproduces with a plain
+# floating pane and no image support required.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+TMUX="$TEST_TMUX -LtestA$$ -f/dev/null"
+TMUX2="$TEST_TMUX -LtestB$$ -f/dev/null"
+
+cleanup()
+{
+	$TMUX kill-server >/dev/null 2>&1
+	$TMUX2 kill-server >/dev/null 2>&1
+}
+fail()
+{
+	echo "$*" >&2
+	cleanup
+	exit 1
+}
+
+# drag STARTCOL STARTROW ENDCOL ENDROW
+#
+# Write a plain (unmodified) SGR button-1 press, drag update and release at
+# 1-based positions to the outer pane holding the inner client - this
+# matches the default MouseDown1Border/MouseDrag1Border bindings used to
+# move or resize a floating pane by its border.
+drag()
+{
+	scol="$1"
+	srow="$2"
+	ecol="$3"
+	erow="$4"
+
+	seq=$(printf '\033[<0;%s;%sM' "$scol" "$srow")
+	$TMUX2 send-keys -t "$OUTER" -l "$seq" 2>/dev/null
+	sleep 0.2
+	seq=$(printf '\033[<32;%s;%sM' "$ecol" "$erow")
+	$TMUX2 send-keys -t "$OUTER" -l "$seq" 2>/dev/null
+	sleep 0.2
+	seq=$(printf '\033[<0;%s;%sm' "$ecol" "$erow")
+	$TMUX2 send-keys -t "$OUTER" -l "$seq" 2>/dev/null
+	sleep 1
+}
+
+cleanup
+
+TMP=$(mktemp)
+trap "cleanup; rm -f $TMP" 0 1 15
+
+$TMUX new-session -d -s inner -x 60 -y 20 'sh -c "sleep 100"' || exit 1
+$TMUX set -g mouse on
+$TMUX set -g default-command 'sh -c "sleep 100"'
+
+FLOAT=$($TMUX new-pane -d -PF '#{pane_id}' -x 16 -y 5 -X 5 -Y 5) ||
+	fail "new-pane -X -Y failed"
+FTOP=$($TMUX display-message -p -t "$FLOAT" '#{pane_top}')
+FLEFT=$($TMUX display-message -p -t "$FLOAT" '#{pane_left}')
+FWIDTH=$($TMUX display-message -p -t "$FLOAT" '#{pane_width}')
+
+$TMUX2 new-session -d -x 60 -y 20 "$TMUX attach -t inner" || exit 1
+sleep 1
+OUTER=$($TMUX2 list-panes -F '#{pane_id}' | head -1)
+[ -n "$OUTER" ] || fail "No outer pane."
+
+# Sanity check: exactly one floating pane, so exactly one top-left corner,
+# before dragging anything.
+$TMUX2 capturep -p -t "$OUTER" >$TMP || fail "capture failed"
+n=$(grep -o '┌' $TMP | wc -l)
+[ "$n" -eq 1 ] || fail "sanity: expected 1 corner before drag, found $n"
+
+# Drag the floating pane by its top border (row FTOP-1, some column within
+# its width) down several rows in a few separate steps, then release. A
+# single drag() call already does press/motion/release, so call it several
+# times in a row to simulate a multi-step real drag.
+GRABCOL=$((FLEFT + FWIDTH / 2))
+STARTROW=$FTOP
+i=0
+while [ $i -lt 6 ]; do
+	newrow=$((STARTROW + i + 1))
+	drag $((GRABCOL + 1)) $((STARTROW + i)) $((GRABCOL + 1)) $newrow
+	i=$((i + 1))
+done
+
+$TMUX2 capturep -p -t "$OUTER" >$TMP || fail "capture failed"
+
+# Exactly one top-left corner should remain - the pane's current position.
+# This is expected to fail before the fix: multiple corners (a trail of
+# un-erased frames) would remain from the intermediate drag positions.
+n=$(grep -o '┌' $TMP | wc -l)
+[ "$n" -eq 1 ] || fail "expected exactly 1 corner after drag, found $n (ghost frames left behind)"
+
+exit 0

regress/floating-pane-drag-no-double-composite.sh

@@ -0,0 +1,88 @@
+#!/bin/sh
+
+# Each drag motion must draw the floating pane content once.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+cd "$DIR" || exit 1
+INNER="$TEST_TMUX -Ldoublecomp-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Ldoublecomp-outer-$$ -f/dev/null"
+
+fail()
+{
+	echo "$*" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	cd /
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+mouse()
+{
+	sequence=$(printf '\033[<%s;%s;%s%s' "$1" "$2" "$3" "$4")
+	$OUTER send-keys -t outer:0.0 -l "$sequence" || exit 1
+	sleep 0.15
+}
+
+$INNER new-session -d -s inner -x 40 -y 15 "printf '\\033[15;1HOUTSIDE'; exec sleep 100" || exit 1
+$INNER set-option -g status off || exit 1
+$INNER set-option -g window-size manual || exit 1
+$INNER set-option -g mouse on || exit 1
+$INNER set-option -g status-interval 0 || exit 1
+$INNER set-option -g automatic-rename off || exit 1
+FLOAT=$($INNER new-pane -d -PF '#{pane_id}' -x 15 -y 5 -X 5 -Y 2 \
+    "printf 'DRAGMARK'; exec sleep 100") || exit 1
+
+$OUTER new-session -d -s outer -x 40 -y 15 'sleep 100' || exit 1
+$OUTER set-option -g status off || exit 1
+$OUTER set-option -g window-size manual || exit 1
+$OUTER set-option -g default-terminal screen-256color || exit 1
+$OUTER respawn-pane -k -t outer:0.0 \
+    "$TEST_TMUX -Ldoublecomp-inner-$$ -f/dev/null attach-session -t inner" ||
+    exit 1
+sleep 0.5
+
+XOFF=$($INNER display-message -p -t "$FLOAT" '#{pane_left}')
+YOFF=$($INNER display-message -p -t "$FLOAT" '#{pane_top}')
+GRABCOL=$((XOFF + 3))
+BORDERROW=$YOFF
+
+# Begin capture after focus changes from the initial mouse press have settled.
+mouse 0 "$GRABCOL" "$BORDERROW" M
+$OUTER pipe-pane -O -t outer:0.0 "cat >'$DIR/output'" || exit 1
+$INNER refresh-client || exit 1
+sleep 0.5
+grep -aq DRAGMARK "$DIR/output" || fail "capture missed floating pane content"
+grep -aq OUTSIDE "$DIR/output" || fail "capture missed untouched row"
+offset=$(wc -c <"$DIR/output")
+
+i=0
+steps=6
+while [ "$i" -lt "$steps" ]; do
+	GRABCOL=$((GRABCOL + 1))
+	mouse 32 "$GRABCOL" "$BORDERROW" M
+	i=$((i + 1))
+done
+mouse 0 "$GRABCOL" "$BORDERROW" m
+sleep 0.3
+
+NEWXOFF=$($INNER display-message -p -t "$FLOAT" '#{pane_left}')
+[ "$NEWXOFF" -eq "$((XOFF + steps))" ] || fail "floating pane did not move six columns"
+tail -c +"$((offset + 1))" "$DIR/output" >"$DIR/drag-output"
+n=$(perl -0777 -ne '$n = () = /DRAGMARK/g; print "$n\n"' "$DIR/drag-output")
+[ "$n" -eq "$steps" ] ||
+	fail "$steps drag motions wrote the floating pane content $n times"
+
+exit 0

regress/floating-pane-drag-scrollbar-strip.sh

@@ -0,0 +1,159 @@
+#!/bin/sh
+
+# Regression test: dragging a floating pane across another pane's ordinary
+# content must not redraw that other pane's scrollbar, unless the drag
+# actually crosses the scrollbar's own strip.
+#
+# cmd_resize_pane_redraw_floating() (cmd-resize-pane.c) used to flag
+# PANE_REDRAWSCROLLBAR on any pane whose whole *body* intersected the
+# floating pane's old or new rectangle, rather than just its narrow
+# scrollbar strip - so dragging a floating pane back and forth over an
+# ordinary tiled pane's content (never touching its scrollbar) still
+# needlessly redrew that pane's scrollbar on every motion step. See
+# tmux-image-redraw-known-bugs.md for the full write-up.
+#
+# This is checked by giving the non-dragged pane a distinctive scrollbar
+# colour and counting how many times its SGR code appears in the client's
+# raw output while the floating pane is dragged vertically over that pane's
+# body, well clear of its scrollbar column: with the fix, it should never
+# reappear after the initial draw.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+TMUX="$TEST_TMUX -LtestA$$ -f/dev/null"
+TMUX2="$TEST_TMUX -LtestB$$ -f/dev/null"
+
+cleanup()
+{
+	$TMUX kill-server >/dev/null 2>&1
+	$TMUX2 kill-server >/dev/null 2>&1
+}
+fail()
+{
+	echo "$*" >&2
+	cleanup
+	exit 1
+}
+
+# drag STARTCOL STARTROW ENDCOL ENDROW
+drag()
+{
+	scol="$1"
+	srow="$2"
+	ecol="$3"
+	erow="$4"
+
+	seq=$(printf '\033[<0;%s;%sM' "$scol" "$srow")
+	$TMUX2 send-keys -t "$OUTER" -l "$seq" 2>/dev/null
+	sleep 0.2
+	seq=$(printf '\033[<32;%s;%sM' "$ecol" "$erow")
+	$TMUX2 send-keys -t "$OUTER" -l "$seq" 2>/dev/null
+	sleep 0.2
+	seq=$(printf '\033[<0;%s;%sm' "$ecol" "$erow")
+	$TMUX2 send-keys -t "$OUTER" -l "$seq" 2>/dev/null
+	sleep 0.5
+}
+
+cleanup
+
+TMP=$(mktemp)
+trap "cleanup; rm -f $TMP" 0 1 15
+
+$TMUX new-session -d -s inner -x 60 -y 20 'sh -c "sleep 100"' || exit 1
+$TMUX set -g mouse on || fail "set mouse failed"
+$TMUX set -g default-command 'sh -c "sleep 100"' || fail "set default-command failed"
+$TMUX set -g pane-scrollbars on || fail "set pane-scrollbars failed"
+
+$TMUX split-window -h -t inner 'sh -c "sleep 100"' || fail "split-window failed"
+
+PANES=$($TMUX list-panes -t inner -F '#{pane_id} #{pane_left}')
+LEFT=$(echo "$PANES" | sort -k2 -n | head -1 | cut -d' ' -f1)
+[ -n "$LEFT" ] || fail "could not identify left pane"
+
+# A distinctive scrollbar colour for the non-dragged (left) pane only.
+$TMUX set -p -t "$LEFT" pane-scrollbars-style 'fg=colour201,bg=colour17' ||
+	fail "set pane-scrollbars-style failed"
+
+ALEFT=$($TMUX display-message -p -t "$LEFT" '#{pane_left}')
+ATOP=$($TMUX display-message -p -t "$LEFT" '#{pane_top}')
+AWIDTH=$($TMUX display-message -p -t "$LEFT" '#{pane_width}')
+AHEIGHT=$($TMUX display-message -p -t "$LEFT" '#{pane_height}')
+[ "$AWIDTH" -gt 15 ] || fail "left pane too narrow for this test ($AWIDTH)"
+
+# A small floating pane placed well inside the left pane's content area,
+# clear of its (right-hand) scrollbar column by several columns.
+FLOAT=$($TMUX new-pane -d -PF '#{pane_id}' -x 8 -y 5 \
+    -X $((ALEFT + 2)) -Y $((ATOP + 2))) || fail "new-pane -X -Y failed"
+FTOP=$($TMUX display-message -p -t "$FLOAT" '#{pane_top}')
+FLEFT=$($TMUX display-message -p -t "$FLOAT" '#{pane_left}')
+FWIDTH=$($TMUX display-message -p -t "$FLOAT" '#{pane_width}')
+[ $((FLEFT + FWIDTH + 3)) -lt $((ALEFT + AWIDTH)) ] ||
+	fail "sanity: floating pane too close to the scrollbar column"
+
+# Start the outer session with a plain shell, then start capturing before
+# triggering the attach - starting the attach as the outer pane's initial
+# command would mean pipe-pane only starts after the attach-driven initial
+# redraw (which draws the scrollbars) has already happened, missing it.
+$TMUX2 new-session -d -x 60 -y 20 || exit 1
+OUTER=$($TMUX2 list-panes -F '#{pane_id}' | head -1)
+[ -n "$OUTER" ] || fail "No outer pane."
+$TMUX2 pipe-pane -t "$OUTER" -O "cat >$TMP" || fail "pipe-pane failed"
+$TMUX2 send-keys -t "$OUTER" -l "$TMUX attach -t inner" || fail "send attach failed"
+$TMUX2 send-keys -t "$OUTER" Enter || fail "send enter failed"
+sleep 1
+
+# Sanity check: the distinctive scrollbar colour reaches the client at all.
+grep -qa '48;5;201' $TMP || fail "sanity: scrollbar colour never reached the client"
+: >$TMP
+
+# Drag the floating pane straight up and down by its top border, staying at
+# a fixed column the whole time - this never crosses the left pane's
+# scrollbar strip, only its ordinary content.
+GRABCOL=$((FLEFT + FWIDTH / 2))
+row=$FTOP
+i=0
+while [ $i -lt 6 ]; do
+	newrow=$((row + 1))
+	drag $GRABCOL $row $GRABCOL $newrow
+	row=$newrow
+	i=$((i + 1))
+done
+i=0
+while [ $i -lt 6 ]; do
+	newrow=$((row - 1))
+	drag $GRABCOL $row $GRABCOL $newrow
+	row=$newrow
+	i=$((i + 1))
+done
+
+# The scrollbar colour should never reappear - its geometry never changed,
+# and the drag never crossed its column. This is expected to fail before
+# the fix - see the header comment.
+n=$(grep -ac '48;5;201' $TMP)
+[ "$n" -eq 0 ] ||
+	fail "left pane's scrollbar was redrawn $n times while dragging over its body only"
+
+# Cross the scrollbar and return, comparing each damaged redraw with a full
+# refresh to check that covering and uncovering its cells leaves no artifacts.
+offset=$((ALEFT + AWIDTH - FLEFT - FWIDTH / 2))
+for delta in "$offset" "$((-offset))"; do
+	oldleft=$($TMUX display-message -p -t "$FLOAT" '#{pane_left}')
+	newcol=$((GRABCOL + delta))
+	drag "$GRABCOL" "$row" "$newcol" "$row"
+	GRABCOL=$newcol
+	newleft=$($TMUX display-message -p -t "$FLOAT" '#{pane_left}')
+	[ "$newleft" -eq "$((oldleft + delta))" ] ||
+		fail "floating pane did not move across the scrollbar as expected"
+	before=$($TMUX2 capture-pane -pe -t "$OUTER" -S 0 -E "$((AHEIGHT - 1))")
+	$TMUX refresh-client || fail "refresh-client failed"
+	sleep 0.5
+	after=$($TMUX2 capture-pane -pe -t "$OUTER" -S 0 -E "$((AHEIGHT - 1))")
+	[ "$before" = "$after" ] ||
+		fail "scrollbar crossing differs from a full redraw"
+done
+
+exit 0

regress/floating-pane-drag-sync-no-self-defer.sh

@@ -0,0 +1,93 @@
+#!/bin/sh
+
+# Synchronized drag output must not cause a full redraw of untouched rows.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+cd "$DIR" || exit 1
+INNER="$TEST_TMUX -Lsyncdefer-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Lsyncdefer-outer-$$ -f/dev/null"
+
+fail()
+{
+	echo "$*" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	cd /
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+mouse()
+{
+	sequence=$(printf '\033[<%s;%s;%s%s' "$1" "$2" "$3" "$4")
+	$OUTER send-keys -t outer:0.0 -l "$sequence" || exit 1
+	sleep 0.15
+}
+
+$INNER new-session -d -s inner -x 40 -y 15 "printf '\\033[15;1HOUTSIDE'; exec sleep 100" || exit 1
+$INNER set-option -g status off || exit 1
+$INNER set-option -g window-size manual || exit 1
+$INNER set-option -g mouse on || exit 1
+$INNER set-option -g status-interval 0 || exit 1
+$INNER set-option -g automatic-rename off || exit 1
+FLOAT=$($INNER new-pane -d -PF '#{pane_id}' -x 15 -y 5 -X 5 -Y 2 \
+    "printf 'DRAGMARK'; exec sleep 100") || exit 1
+
+$OUTER new-session -d -s outer -x 40 -y 15 'sleep 100' || exit 1
+$OUTER set-option -g status off || exit 1
+$OUTER set-option -g window-size manual || exit 1
+$OUTER set-option -g default-terminal screen-256color || exit 1
+$INNER set-option -as terminal-features ',screen-256color:sync' || exit 1
+$OUTER respawn-pane -k -t outer:0.0 \
+    "$TEST_TMUX -Lsyncdefer-inner-$$ -f/dev/null attach-session -t inner" ||
+    exit 1
+sleep 0.5
+
+XOFF=$($INNER display-message -p -t "$FLOAT" '#{pane_left}')
+YOFF=$($INNER display-message -p -t "$FLOAT" '#{pane_top}')
+GRABCOL=$((XOFF + 3))
+BORDERROW=$YOFF
+
+# Begin capture after focus changes from the initial mouse press have settled.
+mouse 0 "$GRABCOL" "$BORDERROW" M
+$OUTER pipe-pane -O -t outer:0.0 "cat >'$DIR/output'" || exit 1
+$INNER refresh-client || exit 1
+sleep 0.5
+grep -aq DRAGMARK "$DIR/output" || fail "capture missed floating pane content"
+grep -aq OUTSIDE "$DIR/output" || fail "capture missed untouched row"
+offset=$(wc -c <"$DIR/output")
+
+i=0
+steps=6
+while [ "$i" -lt "$steps" ]; do
+	GRABCOL=$((GRABCOL + 1))
+	mouse 32 "$GRABCOL" "$BORDERROW" M
+	i=$((i + 1))
+done
+mouse 0 "$GRABCOL" "$BORDERROW" m
+sleep 0.3
+
+NEWXOFF=$($INNER display-message -p -t "$FLOAT" '#{pane_left}')
+[ "$NEWXOFF" -eq "$((XOFF + steps))" ] || fail "floating pane did not move six columns"
+tail -c +"$((offset + 1))" "$DIR/output" >"$DIR/drag-output"
+n=$(perl -0777 -ne '$n = () = /DRAGMARK/g; print "$n\n"' "$DIR/drag-output")
+[ "$n" -ge "$steps" ] || fail "drag output did not reach the client"
+perl -0777 -ne 'exit(/\e\[\?2026h/ ? 0 : 1)' "$DIR/drag-output" ||
+    fail "drag did not use synchronized output"
+if grep -aq OUTSIDE "$DIR/drag-output"; then
+	fail "synchronized drag redrew an untouched row"
+fi
+
+exit 0

regress/floating-pane-drag-wide-character-right.sh

@@ -0,0 +1,206 @@
+#!/bin/sh
+
+# Mirror of floating-pane-drag-wide-character.sh for the *right* edge of a
+# damage rectangle. redraw_damage_grow_span_clip() (screen-redraw.c) widens
+# a damage rectangle's right edge by one cell whenever it isn't already at
+# the span's own edge, to pull in a wide character's base half when the
+# edge lands on its padding half - but it did this unconditionally, with no
+# check of which half it was actually touching. When the edge instead
+# already lands cleanly on a fresh character's base cell (a character fully
+# outside the range), growing right pulls in just that base cell -
+# tty_draw_line() sees it can't fit that character's full width in the
+# remaining range (tty_draw_line_get_empty()'s gc->data.width > nx check)
+# and clears it, exactly as the left-edge bug cleared a neighbouring
+# character's padding half.
+#
+# As with the left-edge test, the exact column parity needs to be
+# deterministic to actually catch it. This constructs it by creating the
+# floating pane, checking its real position, and recreating it one column
+# over if necessary until the vacated rectangle's right edge lands on a
+# base cell.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+INNER="$TEST_TMUX -Lwidecharr-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Lwidecharr-outer-$$ -f/dev/null"
+EMITTER=$DIR/emitter.pl
+BASE=$DIR/base
+CAPTURE=$DIR/capture
+FLOAT=
+PANEWIDTH=12
+
+fail()
+{
+	echo "$*" >&2
+	[ -s "$CAPTURE" ] && cat "$CAPTURE" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+wait_for_client()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		CLIENT=$($INNER list-clients -F '#{client_name}' 2>/dev/null)
+		[ -n "$CLIENT" ] && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "inner client did not attach"
+}
+
+wait_outer_has()
+{
+	marker=$1
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t outer:0.0 >"$CAPTURE" 2>/dev/null || true
+		grep -q "$marker" "$CAPTURE" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "outer client did not show $marker"
+}
+
+slice_columns()
+{
+	# Extract terminal columns [COL1, COL2) from lines [ROW1, ROW2] of
+	# $1, decoding UTF-8 - the pane's own new position (well clear of
+	# this range) must not affect the comparison, so this only looks at
+	# the narrow strip actually vacated, not the whole line. capture-pane
+	# text has one decoded character per double-width cell pair (every
+	# character here is width 2), so terminal columns are converted to
+	# character indices by halving before slicing.
+	perl -CSD -e '
+		my ($row1, $row2, $col1, $col2, $file) = @ARGV;
+		open my $fh, "<:encoding(UTF-8)", $file or die $!;
+		my @lines = <$fh>;
+		my $c1 = int($col1 / 2);
+		my $c2 = int(($col2 + 1) / 2);
+		for my $n ($row1 .. $row2) {
+			my $line = $lines[$n - 1];
+			$line =~ s/\R\z//;
+			print substr($line, $c1, $c2 - $c1), "\n";
+		}
+	' "$ROW1" "$ROW2" "$COL1" "$COL2" "$1"
+}
+
+wait_old_rows_restored()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t outer:0.0 >"$CAPTURE" 2>/dev/null || true
+		slice_columns "$BASE" >"$DIR/want"
+		slice_columns "$CAPTURE" >"$DIR/got"
+		cmp -s "$DIR/want" "$DIR/got" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "wide characters under the floating pane's vacated right edge were not restored"
+}
+
+mouse()
+{
+	sequence=$(printf '\033[<%s;%s;%s%s' "$1" "$2" "$3" "$4")
+	$OUTER send-keys -t outer:0.0 -l "$sequence" || exit 1
+	sleep 0.1
+}
+
+cat >"$EMITTER" <<'PERL'
+use strict;
+use warnings;
+
+binmode STDOUT, ':encoding(UTF-8)';
+$| = 1;
+for my $row (1 .. 10) {
+	print "\e[$row;1H", chr(0x754c) x 20;
+}
+sleep 100;
+PERL
+
+$INNER new-session -d -s inner -x 40 -y 10 "perl '$EMITTER'" || exit 1
+$INNER set-option -g status off || exit 1
+$INNER set-option -g window-size manual || exit 1
+$INNER set-option -g mouse on || exit 1
+$INNER set-option -g pane-scrollbars off || exit 1
+
+$OUTER new-session -d -s outer -x 40 -y 10 'sleep 100' || exit 1
+$OUTER set-option -g status off || exit 1
+$OUTER set-option -g window-size manual || exit 1
+$OUTER set-option -g default-terminal screen-256color || exit 1
+$OUTER respawn-pane -k -t outer:0.0 \
+    "$TEST_TMUX -Lwidecharr-inner-$$ -f/dev/null attach-session -t inner" ||
+    exit 1
+
+wait_for_client
+wait_outer_has '界界界'
+$OUTER capture-pane -p -t outer:0.0 >"$BASE" || exit 1
+
+# Create the floating pane, then check its actual resulting position. Try
+# adjacent starting columns until the vacated rectangle's right edge
+# (xoff + PANEWIDTH + 1, the border-grown exclusive end - see
+# window_pane_damage_floating(), window.c) lands on an even (base-cell)
+# column.
+startx=5
+tries=0
+while [ "$tries" -lt 2 ]; do
+	[ -n "$FLOAT" ] && $INNER kill-pane -t "$FLOAT" 2>/dev/null
+	FLOAT=$($INNER new-pane -d -PF '#{pane_id}' -x "$PANEWIDTH" -y 3 \
+	    -X "$startx" -Y 5 \
+	    'sh -c "printf FLOATMARK; exec sleep 100"') || exit 1
+	sleep 0.2
+	XOFF=$($INNER display-message -p -t "$FLOAT" '#{pane_left}')
+	YOFF=$($INNER display-message -p -t "$FLOAT" '#{pane_top}')
+	oldright=$((XOFF + PANEWIDTH + 1))
+	if [ $((oldright % 2)) -eq 0 ]; then
+		break
+	fi
+	startx=$((startx + 1))
+	tries=$((tries + 1))
+done
+[ $(((XOFF + PANEWIDTH + 1) % 2)) -eq 0 ] ||
+	fail "could not find bad-parity starting column"
+
+wait_outer_has FLOATMARK
+
+ROW1=$((YOFF + 1))
+ROW2=$((YOFF + 3))
+COL1=$((XOFF + PANEWIDTH - 2))
+COL2=$((XOFF + PANEWIDTH + 2))
+
+# Grab the pane's top border a couple of columns in (avoiding the corner
+# cells) and drag it well clear of its old rectangle - far enough right
+# that its new position starts past the checked columns above (which sit
+# just past the pane's *original* right edge).
+GRABCOL=$((XOFF + 3))
+BORDERROW=$((YOFF))
+
+seq=$(printf '\033[<0;%s;%sM' "$GRABCOL" "$BORDERROW")
+$OUTER send-keys -t outer:0.0 -l "$seq" || exit 1
+sleep 0.1
+seq=$(printf '\033[<32;%s;%sM' "$((GRABCOL + 20))" "$BORDERROW")
+$OUTER send-keys -t outer:0.0 -l "$seq" || exit 1
+sleep 0.1
+seq=$(printf '\033[<0;%s;%sm' "$((GRABCOL + 20))" "$BORDERROW")
+$OUTER send-keys -t outer:0.0 -l "$seq" || exit 1
+sleep 0.1
+
+NEWXOFF=$($INNER display-message -p -t "$FLOAT" '#{pane_left}')
+[ "$NEWXOFF" != "$XOFF" ] || fail "sanity: floating pane did not move (still at $XOFF)"
+
+wait_old_rows_restored
+
+exit 0

regress/floating-pane-drag-wide-character.sh

@@ -0,0 +1,200 @@
+#!/bin/sh
+
+# Damage at a floating pane's vacated edge must always redraw a complete
+# grid character. redraw_damage_grow_span_clip() (screen-redraw.c) widens a
+# damage rectangle's left edge by one cell whenever it isn't already at the
+# span's own edge, to pull in a wide character's base half when the edge
+# lands on its padding half - but it did this unconditionally, with no
+# check of which half it was actually touching. When the edge instead
+# already lands cleanly on a fresh character's base cell, growing left
+# walks into the *previous*, unrelated character's padding cell and blanks
+# it (tty_draw_line() treats any leading padding cell as proof its own
+# range starts mid-character).
+#
+# This is a general damage-composition bug, not specific to any one kind of
+# pane, but the exact column parity needs to be deterministic to actually
+# catch it (a lucky parity draws fine). This constructs it by creating the
+# floating pane, checking its real position (the border-framing offset
+# added to -X is not something to hand-compute), and recreating it one
+# column over if necessary until the vacated rectangle's left edge lands on
+# a base cell.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+INNER="$TEST_TMUX -Lwidechar-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Lwidechar-outer-$$ -f/dev/null"
+EMITTER=$DIR/emitter.pl
+BASE=$DIR/base
+CAPTURE=$DIR/capture
+FLOAT=
+
+fail()
+{
+	echo "$*" >&2
+	[ -s "$CAPTURE" ] && cat "$CAPTURE" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+wait_for_client()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		CLIENT=$($INNER list-clients -F '#{client_name}' 2>/dev/null)
+		[ -n "$CLIENT" ] && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "inner client did not attach"
+}
+
+wait_outer_has()
+{
+	marker=$1
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t outer:0.0 >"$CAPTURE" 2>/dev/null || true
+		grep -q "$marker" "$CAPTURE" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "outer client did not show $marker"
+}
+
+slice_columns()
+{
+	# Extract terminal columns [COL1, COL2) from lines [ROW1, ROW2] of
+	# $1, decoding UTF-8 - the pane's own new position (well clear of
+	# this range) must not affect the comparison, so this only looks at
+	# the narrow strip actually vacated, not the whole line. capture-pane
+	# text has one decoded character per double-width cell pair (every
+	# character here is width 2), so terminal columns are converted to
+	# character indices by halving before slicing.
+	perl -CSD -e '
+		my ($row1, $row2, $col1, $col2, $file) = @ARGV;
+		open my $fh, "<:encoding(UTF-8)", $file or die $!;
+		my @lines = <$fh>;
+		my $c1 = int($col1 / 2);
+		my $c2 = int(($col2 + 1) / 2);
+		for my $n ($row1 .. $row2) {
+			my $line = $lines[$n - 1];
+			$line =~ s/\R\z//;
+			print substr($line, $c1, $c2 - $c1), "\n";
+		}
+	' "$ROW1" "$ROW2" "$COL1" "$COL2" "$1"
+}
+
+wait_old_rows_restored()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t outer:0.0 >"$CAPTURE" 2>/dev/null || true
+		slice_columns "$BASE" >"$DIR/want"
+		slice_columns "$CAPTURE" >"$DIR/got"
+		cmp -s "$DIR/want" "$DIR/got" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "wide characters under the floating pane's vacated edge were not restored"
+}
+
+mouse()
+{
+	sequence=$(printf '\033[<%s;%s;%s%s' "$1" "$2" "$3" "$4")
+	$OUTER send-keys -t outer:0.0 -l "$sequence" || exit 1
+	sleep 0.1
+}
+
+cat >"$EMITTER" <<'PERL'
+use strict;
+use warnings;
+
+binmode STDOUT, ':encoding(UTF-8)';
+$| = 1;
+for my $row (1 .. 10) {
+	print "\e[$row;1H", chr(0x754c) x 20;
+}
+sleep 100;
+PERL
+
+$INNER new-session -d -s inner -x 40 -y 10 "perl '$EMITTER'" || exit 1
+$INNER set-option -g status off || exit 1
+$INNER set-option -g window-size manual || exit 1
+$INNER set-option -g mouse on || exit 1
+$INNER set-option -g pane-scrollbars off || exit 1
+
+$OUTER new-session -d -s outer -x 40 -y 10 'sleep 100' || exit 1
+$OUTER set-option -g status off || exit 1
+$OUTER set-option -g window-size manual || exit 1
+$OUTER set-option -g default-terminal screen-256color || exit 1
+$OUTER respawn-pane -k -t outer:0.0 \
+    "$TEST_TMUX -Lwidechar-inner-$$ -f/dev/null attach-session -t inner" ||
+    exit 1
+
+wait_for_client
+wait_outer_has '界界界'
+$OUTER capture-pane -p -t outer:0.0 >"$BASE" || exit 1
+
+# Create the floating pane, then check its actual resulting position. Try
+# adjacent starting columns until the vacated rectangle's left edge
+# (xoff - 1) lands on an even (base-cell) column - the odd case is the one
+# every earlier manual test happened to land on by chance.
+startx=5
+tries=0
+while [ "$tries" -lt 2 ]; do
+	[ -n "$FLOAT" ] && $INNER kill-pane -t "$FLOAT" 2>/dev/null
+	FLOAT=$($INNER new-pane -d -PF '#{pane_id}' -x 12 -y 3 -X "$startx" \
+	    -Y 5 'sh -c "printf FLOATMARK; exec sleep 100"') || exit 1
+	sleep 0.2
+	XOFF=$($INNER display-message -p -t "$FLOAT" '#{pane_left}')
+	YOFF=$($INNER display-message -p -t "$FLOAT" '#{pane_top}')
+	oldleft=$((XOFF - 1))
+	if [ $((oldleft % 2)) -eq 0 ]; then
+		break
+	fi
+	startx=$((startx + 1))
+	tries=$((tries + 1))
+done
+[ $(((XOFF - 1) % 2)) -eq 0 ] || fail "could not find bad-parity starting column"
+
+wait_outer_has FLOATMARK
+
+ROW1=$((YOFF + 1))
+ROW2=$((YOFF + 3))
+COL1=$((XOFF - 4))
+COL2=$((XOFF + 4))
+
+# Grab the pane's top border a couple of columns in (avoiding the corner
+# cells) and drag it well clear of its old rectangle.
+GRABCOL=$((XOFF + 3))
+BORDERROW=$((YOFF))
+
+seq=$(printf '\033[<0;%s;%sM' "$GRABCOL" "$BORDERROW")
+$OUTER send-keys -t outer:0.0 -l "$seq" || exit 1
+sleep 0.1
+seq=$(printf '\033[<32;%s;%sM' "$((GRABCOL + 15))" "$BORDERROW")
+$OUTER send-keys -t outer:0.0 -l "$seq" || exit 1
+sleep 0.1
+seq=$(printf '\033[<0;%s;%sm' "$((GRABCOL + 15))" "$BORDERROW")
+$OUTER send-keys -t outer:0.0 -l "$seq" || exit 1
+sleep 0.1
+
+NEWXOFF=$($INNER display-message -p -t "$FLOAT" '#{pane_left}')
+[ "$NEWXOFF" != "$XOFF" ] || fail "sanity: floating pane did not move (still at $XOFF)"
+
+wait_old_rows_restored
+
+exit 0

regress/floating-pane-offscreen-alternate-redraw.sh

@@ -0,0 +1,102 @@
+#!/bin/sh
+
+# Returning from the alternate screen must redraw the visible part of a
+# floating pane clipped at the left edge, the top edge, or both.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+INNER="$TEST_TMUX -Loffscreen-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Loffscreen-outer-$$ -f/dev/null"
+EMITTER=$DIR/emitter.pl
+CAPTURE=$DIR/capture
+
+fail()
+{
+	echo "$*" >&2
+	[ -s "$CAPTURE" ] && cat "$CAPTURE" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+wait_outer_has()
+{
+	marker=$1
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t outer:0.0 >"$CAPTURE" 2>/dev/null || true
+		grep -q "$marker" "$CAPTURE" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "outer client did not show $marker"
+}
+
+cat >"$EMITTER" <<'PERL'
+use strict;
+use warnings;
+
+$| = 1;
+for my $row (1 .. 5) {
+	print "\e[$row;1H", 'A' x 15;
+}
+while (!-e "$ENV{TRIGGER}-alternate") {
+	select undef, undef, undef, 0.01;
+}
+print "\e[?1049h";
+for my $row (1 .. 5) {
+	print "\e[$row;1H", 'B' x 15;
+}
+while (!-e "$ENV{TRIGGER}-restore") {
+	select undef, undef, undef, 0.01;
+}
+print "\e[?1049l";
+sleep 100;
+PERL
+
+$INNER new-session -d -s inner -x 40 -y 10 'sleep 100' || exit 1
+$INNER set-option -g status off || exit 1
+$INNER set-option -g window-size manual || exit 1
+
+$OUTER new-session -d -s outer -x 40 -y 10 'sleep 100' || exit 1
+$OUTER set-option -g status off || exit 1
+$OUTER set-option -g window-size manual || exit 1
+$OUTER set-option -g default-terminal screen-256color || exit 1
+$OUTER respawn-pane -k -t outer:0.0 \
+    "$TEST_TMUX -Loffscreen-inner-$$ -f/dev/null attach-session -t inner" ||
+    exit 1
+
+for position in left top both; do
+	case "$position" in
+	left) x=-5; y=2 ;;
+	top) x=5; y=-2 ;;
+	both) x=-5; y=-2 ;;
+	esac
+	FLOAT=$($INNER new-pane -d -PF '#{pane_id}' -x 15 -y 5 -X "$x" -Y "$y" \
+	    "TRIGGER='$DIR/$position' perl '$EMITTER'") || exit 1
+	[ "$($INNER display-message -p -t "$FLOAT" '#{pane_left},#{pane_top}')" = "$((x + 1)),$((y + 1))" ] ||
+	    fail "$position: floating pane has unexpected position"
+	wait_outer_has AAAAA
+	cp "$CAPTURE" "$DIR/primary"
+	: >"$DIR/$position-alternate"
+	wait_outer_has BBBBB
+	: >"$DIR/$position-restore"
+	wait_outer_has AAAAA
+	cmp -s "$DIR/primary" "$CAPTURE" ||
+	    fail "$position: primary screen was not completely restored"
+	$INNER kill-pane -t "$FLOAT" || exit 1
+done
+
+exit 0

regress/floating-pane-prompt-wide-character.sh

@@ -0,0 +1,179 @@
+#!/bin/sh
+
+# A damage rectangle's clip range is grown to avoid splitting a wide
+# character, but redraw_damage_grow_span_clip() (screen-redraw.c) only ever
+# checks the span's own pane *content* grid (wp->screen) for that. For a
+# REDRAW_SPAN_PANE span, that same range is then also handed to
+# redraw_damage_draw_pane_prompt() to recompose the pane's separately
+# rendered prompt (wp->prompt, e.g. from "command-prompt -P") over the
+# damaged sub-range - but the prompt is drawn into its own, freshly
+# allocated one-line screen, unrelated to the pane's content grid, so a
+# range grown (or left ungrown) against the content is not necessarily
+# grown correctly for the prompt's own wide characters.
+#
+# This is invisible when the pane's own content is plain ASCII (as here):
+# redraw_damage_grow_span_clip() never finds anything to grow against, so
+# the raw, ungrown geometric range is passed straight through to the
+# prompt - and if that range's edge lands mid-character in the *prompt's*
+# grid, tty_draw_line() clears the character it cuts through
+# (tty_draw_line_get_empty()'s gc->data.width > nx check, for a trailing
+# base cell with no room left for its padding half).
+#
+# The trigger is a palette change (OSC 4) in a tiled pane that is one half
+# of a vertical split running the full height of the window - occluded
+# under the floating pane, but still geometrically triggering a redraw of
+# its own rectangle. Positioned so the split boundary falls inside the
+# floating pane's own CJK prompt, this reproduces exactly Codex's report:
+# "a floating pane containing a CJK prompt across a tiled-pane boundary -
+# a palette update in the tiled pane blanks a prompt character."
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+cd "$DIR" || exit 1
+INNER="$TEST_TMUX -Lpromptwide-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Lpromptwide-outer-$$ -f/dev/null"
+EMITTER=$DIR/emitter.pl
+CAPTURE=$DIR/capture
+FLOAT=
+
+fail()
+{
+	echo "$*" >&2
+	[ -s "$CAPTURE" ] && cat "$CAPTURE" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	cd /
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+wait_for_client()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		CLIENT=$($INNER list-clients -F '#{client_name}' 2>/dev/null)
+		[ -n "$CLIENT" ] && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "inner client did not attach"
+}
+
+wait_outer_has()
+{
+	marker=$1
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t outer:0.0 >"$CAPTURE" 2>/dev/null || true
+		grep -q "$marker" "$CAPTURE" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "outer client did not show $marker"
+}
+
+wait_prompt_row_intact()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t outer:0.0 >"$CAPTURE" 2>/dev/null || true
+		line=$(sed -n "${PROMPTROW}p" "$CAPTURE")
+		case $line in
+		*"$PROMPTTEXT"*) return 0 ;;
+		esac
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "the CJK prompt was not intact after the palette-triggered damage - got: $line"
+}
+
+cat >"$EMITTER" <<'PERL'
+use strict;
+use warnings;
+
+$| = 1;
+my $line = <STDIN>;
+print "\e]4;1;rgb:11/22/33\e\\";
+sleep 100;
+PERL
+
+$INNER new-session -d -s inner -x 60 -y 12 "perl '$EMITTER'" || exit 1
+$INNER set-option -g status off || exit 1
+$INNER set-option -g window-size manual || exit 1
+LEFT=$($INNER list-panes -t inner -F '#{pane_id}') || exit 1
+
+# Split so the boundary between the two tiled panes falls at column 17 -
+# used below to pick a floating-pane column that lands the boundary
+# mid-character inside the prompt.
+RIGHT=$($INNER split-window -t inner -h -l 43 -PF '#{pane_id}' \
+    'sleep 100') || exit 1
+RX=$($INNER display-message -p -t "$RIGHT" '#{pane_left}') || exit 1
+
+# Create the floating pane, then check its actual resulting position (the
+# border-framing offset added to -X is not something to hand-compute). Try
+# adjacent starting columns until the split boundary lands on an odd
+# (padding-half) column of the prompt's own numbering, and within the
+# prompt's 12-column width.
+startx=10
+tries=0
+while [ "$tries" -lt 4 ]; do
+	[ -n "$FLOAT" ] && $INNER kill-pane -t "$FLOAT" 2>/dev/null
+	FLOAT=$($INNER new-pane -d -PF '#{pane_id}' -x 24 -y 5 -X "$startx" \
+	    -Y 2 "sh -c 'i=0; while [ \$i -lt 10 ]; do \
+printf AAAAAAAAAAAAAAAAAAAAAA\\\\n; i=\$((i+1)); done; sleep 100'") ||
+	    exit 1
+	sleep 0.2
+	X1=$($INNER display-message -p -t "$FLOAT" '#{pane_left}')
+	Y1=$($INNER display-message -p -t "$FLOAT" '#{pane_top}')
+	H1=$($INNER display-message -p -t "$FLOAT" '#{pane_height}')
+	local=$((RX - X1 - 1))
+	if [ "$local" -ge 1 ] && [ "$local" -le 11 ] &&
+	    [ $((local % 2)) -eq 1 ]; then
+		break
+	fi
+	startx=$((startx + 1))
+	tries=$((tries + 1))
+done
+local=$((RX - X1 - 1))
+[ "$local" -ge 1 ] && [ "$local" -le 11 ] && [ $((local % 2)) -eq 1 ] ||
+	fail "could not find bad-parity starting column"
+
+$OUTER new-session -d -s outer -x 60 -y 12 'sleep 100' || exit 1
+$OUTER set-option -g status off || exit 1
+$OUTER set-option -g window-size manual || exit 1
+$OUTER set-option -g default-terminal screen-256color || exit 1
+$OUTER respawn-pane -k -t outer:0.0 \
+    "$TEST_TMUX -Lpromptwide-inner-$$ -f/dev/null attach-session -t inner" ||
+    exit 1
+
+wait_for_client
+wait_outer_has AAAAAAAAAAAAAAAAAAAAAA
+CLIENT=$($INNER list-clients -F '#{client_name}') || exit 1
+
+$INNER select-pane -t "$FLOAT" || exit 1
+PROMPTTEXT=$(printf '\344\270\255' | perl -CSD -ne 'print $_ x 6')
+$INNER command-prompt -b -P -t "$CLIENT" -p "$PROMPTTEXT" \
+    'display-message -- %1' || exit 1
+wait_outer_has "$PROMPTTEXT"
+
+PROMPTROW=$((Y1 + H1))
+
+# Trigger the damage: unblock the emitter so it fires the palette change in
+# the left tiled pane, which is occluded under (but geometrically overlaps)
+# the floating pane's prompt row.
+$INNER send-keys -t "$LEFT" Enter || exit 1
+
+wait_prompt_row_intact
+
+exit 0

regress/floating-pane-status-cross-client.sh

@@ -0,0 +1,151 @@
+#!/bin/sh
+
+# Damage redraws must show each client's own pane status, even though the
+# cached status screen is shared between clients.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+INNER="$TEST_TMUX -Lstatuscc-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Lstatuscc-outer-$$ -f/dev/null"
+CAPTURE=$DIR/capture
+
+fail()
+{
+	echo "$*" >&2
+	[ -s "$CAPTURE" ] && cat "$CAPTURE" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+wait_for_clients()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		count=$($INNER list-clients 2>/dev/null | wc -l)
+		[ "$count" -eq 2 ] && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "two inner clients did not attach"
+}
+
+wait_for_marker()
+{
+	target=$1
+	marker=$2
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t "$target" >"$CAPTURE" || exit 1
+		grep -q "$marker" "$CAPTURE" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "client in $target did not receive $marker"
+}
+
+cat >"$DIR/emitter.pl" <<'PERL'
+use strict;
+use warnings;
+
+$| = 1;
+for my $phase (1 .. 4) {
+	while (!-e "$ENV{TRIGGER}-$phase") {
+		select undef, undef, undef, 0.01;
+	}
+	# Change an unused palette entry and acknowledge it in the pane body.
+	print "\e]4;200;rgb:11/22/0$phase\a\e[1;1HDAMAGE$phase";
+}
+sleep 100;
+PERL
+
+$INNER new-session -d -s inner -x 60 -y 20 \
+    "TRIGGER='$DIR/trigger' perl '$DIR/emitter.pl'" || exit 1
+$INNER set -g status off || exit 1
+$INNER set -g window-size manual || exit 1
+$INNER set -g automatic-rename off || exit 1
+$INNER set -g status-interval 0 || exit 1
+$INNER set -g pane-border-lines simple || exit 1
+$INNER set -g pane-border-status top || exit 1
+$INNER set -g pane-border-format 'CLIENT=<#{client_name}>' || exit 1
+FLOAT=$($INNER new-pane -d -PF '#{pane_id}' -x 35 -y 6 -X 5 -Y 5 \
+    'sleep 100') || exit 1
+
+$OUTER new-session -d -s outer -x 121 -y 20 'sleep 100' || exit 1
+$OUTER set -g status off || exit 1
+$OUTER set -g window-size manual || exit 1
+$OUTER set -g default-terminal screen || exit 1
+LEFT=$($OUTER display-message -p -t outer:0.0 '#{pane_id}') || exit 1
+RIGHT=$($OUTER split-window -h -PF '#{pane_id}' 'sleep 100') || exit 1
+for target in "$LEFT" "$RIGHT"; do
+	$OUTER respawn-pane -k -t "$target" "$INNER attach-session -t inner" ||
+	    exit 1
+done
+wait_for_clients
+
+NAME1=$($OUTER display-message -p -t "$LEFT" '#{pane_tty}') || exit 1
+NAME2=$($OUTER display-message -p -t "$RIGHT" '#{pane_tty}') || exit 1
+
+# Disable periodic status updates above and trigger damage without a command
+# that also requests a status redraw. Each client must keep its own title.
+$INNER refresh-client -t "$NAME1" || exit 1
+$INNER refresh-client -t "$NAME2" || exit 1
+sleep 0.5
+for phase in 0 1 2; do
+	if [ "$phase" -ne 0 ]; then
+		: >"$DIR/trigger-$phase"
+		wait_for_marker "$LEFT" "DAMAGE$phase"
+		wait_for_marker "$RIGHT" "DAMAGE$phase"
+		sleep 0.2
+	fi
+	for target in "$LEFT" "$RIGHT"; do
+		if [ "$target" = "$LEFT" ]; then
+			name=$NAME1
+			other=$NAME2
+		else
+			name=$NAME2
+			other=$NAME1
+		fi
+		$OUTER capture-pane -p -S 5 -E 10 -t "$target" \
+		    >"$CAPTURE" || exit 1
+		grep -Fq "CLIENT=<$name>" "$CAPTURE" ||
+		    fail "phase $phase: missing $name's pane status"
+		if grep -Fq "CLIENT=<$other>" "$CAPTURE"; then
+			fail "phase $phase: $name received $other's pane status"
+		fi
+	done
+done
+
+# Leave just one client so a cache keyed only by client would remain stale.
+$OUTER respawn-pane -k -t "$RIGHT" 'sleep 100' || exit 1
+i=0
+while [ "$($INNER list-clients | wc -l)" -ne 1 ]; do
+	[ "$i" -lt 50 ] || fail "second client did not detach"
+	sleep 0.1
+	i=$((i + 1))
+done
+$INNER set-environment -g TEST_STATUS_VALUE initial || exit 1
+$INNER set -g pane-border-format 'VALUE=#{TEST_STATUS_VALUE}' || exit 1
+$INNER refresh-client -t "$NAME1" || exit 1
+wait_for_marker "$LEFT" VALUE=initial
+for phase in 3 4; do
+	# Changing the environment does not itself request a status redraw.
+	$INNER set-environment -g TEST_STATUS_VALUE "phase$phase" || exit 1
+	: >"$DIR/trigger-$phase"
+	wait_for_marker "$LEFT" "DAMAGE$phase"
+	wait_for_marker "$LEFT" "VALUE=phase$phase"
+done
+
+exit 0

regress/floating-pane-status-format.sh

@@ -0,0 +1,102 @@
+#!/bin/sh
+
+# Resizing a floating pane must refresh session status formats which depend on
+# its geometry, not only the pane scene and borders.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+INNER="$TEST_TMUX -Lfloating-status-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Lfloating-status-outer-$$ -f/dev/null"
+CAPTURE=$DIR/capture
+
+fail()
+{
+	echo "$*" >&2
+	[ -s "$CAPTURE" ] && cat "$CAPTURE" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+wait_for_client()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		CLIENT=$($INNER list-clients -F '#{client_name}' 2>/dev/null)
+		[ -n "$CLIENT" ] && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "inner client did not attach"
+}
+
+wait_outer_has_status()
+{
+	marker=$1
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t outer:0.0 >"$CAPTURE" 2>/dev/null || true
+		tail -1 "$CAPTURE" | grep -q "$marker" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "outer client status did not show $marker"
+}
+
+mouse()
+{
+	sequence=$(printf '\033[<%s;%s;%s%s' "$1" "$2" "$3" "$4")
+	$OUTER send-keys -t outer:0.0 -l "$sequence" || exit 1
+	sleep 0.1
+}
+
+$INNER new-session -d -s inner -x 50 -y 12 'sleep 100' || exit 1
+FLOAT=$($INNER new-pane -PF '#{pane_id}' -x 10 -y 5 -X 5 -Y 3 \
+    'sleep 100') || fail "could not create floating pane"
+$INNER set-option -g window-size manual || exit 1
+$INNER set-option -g mouse on || exit 1
+$INNER set-option -g status on || exit 1
+$INNER set-option -g status-position bottom || exit 1
+$INNER set-option -g status-left 'WIDTH=#{pane_width}' || exit 1
+$INNER set-option -g status-right '' || exit 1
+$INNER set-option -g status-interval 0 || exit 1
+
+$OUTER new-session -d -s outer -x 50 -y 12 'sleep 100' || exit 1
+$OUTER set-option -g status off || exit 1
+$OUTER set-option -g window-size manual || exit 1
+$OUTER respawn-pane -k -t outer:0.0 \
+    "$TEST_TMUX -Lfloating-status-inner-$$ -f/dev/null attach-session -t inner" ||
+    exit 1
+
+wait_for_client
+OLD_WIDTH=$($INNER display-message -p -t "$FLOAT" '#{pane_width}')
+wait_outer_has_status "WIDTH=$OLD_WIDTH"
+
+RIGHT=$($INNER display-message -p -t "$FLOAT" '#{pane_right}')
+TOP=$($INNER display-message -p -t "$FLOAT" '#{pane_top}')
+X=$((RIGHT + 2))
+Y=$((TOP + 2))
+
+# Grab the right frame and enlarge the floating pane.
+mouse 0 "$X" "$Y" M
+mouse 32 "$((X + 1))" "$Y" M
+mouse 32 "$((X + 8))" "$Y" M
+mouse 0 "$((X + 8))" "$Y" m
+
+NEW_WIDTH=$($INNER display-message -p -t "$FLOAT" '#{pane_width}')
+[ "$NEW_WIDTH" -ne "$OLD_WIDTH" ] || fail "floating pane was not resized"
+wait_outer_has_status "WIDTH=$NEW_WIDTH"
+
+exit 0

regress/format-fuzzy.sh

@@ -7,6 +7,8 @@ TERM=screen
 
 [ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
 TMUX="$TEST_TMUX -LtestA$$ -f/dev/null"
+trap '$TMUX kill-server 2>/dev/null' 0
+trap 'exit 1' 1 2 15
 
 # test_format $format $expected_result
 test_format()

regress/format-modifiers.sh

@@ -18,6 +18,24 @@ export TZ LANG LC_ALL
 
 [ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
 TMUX="$TEST_TMUX -LtestA$$ -f/dev/null"
+FIFO1="${TMPDIR:-/tmp}/fmt-l-$$-1"
+FIFO2="${TMPDIR:-/tmp}/fmt-l-$$-2"
+HOLD1=
+HOLD2=
+CC1=
+CC2=
+
+cleanup()
+{
+	for pid in $HOLD1 $HOLD2 $CC1 $CC2; do
+		kill "$pid" 2>/dev/null
+		wait "$pid" 2>/dev/null
+	done
+	$TMUX kill-server 2>/dev/null
+	rm -f "$FIFO1" "$FIFO2"
+}
+trap cleanup 0
+trap 'exit 1' 1 2 15
 
 ESC=$(printf '\033')
 
@@ -579,8 +597,6 @@ assert_alive "verbose loop expansion"
 
 # L loops over attached clients.  Attach two control-mode clients, each held
 # open by a background process keeping a FIFO's write end open.
-FIFO1="${TMPDIR:-/tmp}/fmt-l-$$-1"
-FIFO2="${TMPDIR:-/tmp}/fmt-l-$$-2"
 rm -f "$FIFO1" "$FIFO2"
 mkfifo "$FIFO1" "$FIFO2" || exit 1
 # Hold the write ends open so the control clients stay attached.
@@ -605,9 +621,9 @@ test_format "#{L/nr:x}" "xx"
 test_format "#{L/r:x}" "xx"
 # Now detach one and confirm the count drops to one.
 kill $HOLD2 2>/dev/null
+wait $HOLD2 2>/dev/null
+HOLD2=
 sleep 1
 test_format "#{L:x}" "x"
-kill $HOLD1 $CC1 $CC2 2>/dev/null
-rm -f "$FIFO1" "$FIFO2"
 
 exit 0

regress/format-strings.sh

@@ -7,6 +7,8 @@ TERM=screen
 
 [ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
 TMUX="$TEST_TMUX -LtestA$$ -f/dev/null"
+trap '$TMUX kill-server 2>/dev/null' 0
+trap 'exit 1' 1 2 15
 
 # test_format $format $expected_result
 test_format()

regress/hooks-lifecycle.sh

@@ -76,14 +76,14 @@ $TMUX set-hook -g session-closed \
 	fail "set-hook session-closed failed"
 
 # The only pane of the only window of a session exits: pane-exited, then
-# window-unlinked, then session-closed, each seeing the dead object in the
+# session-closed, then window-unlinked, each seeing the dead object in the
 # hook formats.
 pane=$($TMUX new -d -s doomed -n dwin -P -F '#{pane_id}' 'true') ||
 	fail "new-session doomed failed"
 wait_for @log \
-	"|pane-exited:$pane|window-unlinked:doomed:dwin|session-closed:doomed"
+	"|pane-exited:$pane|session-closed:doomed|window-unlinked:doomed:dwin"
 assert_unchanged @log \
-	"|pane-exited:$pane|window-unlinked:doomed:dwin|session-closed:doomed"
+	"|pane-exited:$pane|session-closed:doomed|window-unlinked:doomed:dwin"
 
 # The dead pane, window and session cannot be used as targets but the
 # server survives.
@@ -110,14 +110,14 @@ $TMUX set-hook -g pane-exited \
 	'set -gF @log "#{@log}|pane-exited:#{hook_pane}"' ||
 	fail "restore pane-exited hook failed"
 
-# kill-window on the last window: window-unlinked then session-closed but
+# kill-window on the last window: session-closed then window-unlinked but
 # no pane-exited for the panes in the killed window.
 $TMUX set -g @log '' || fail "reset @log failed"
 $TMUX new -d -s doomed2 -n dwin2 || fail "new-session doomed2 failed"
 $TMUX splitw -d -t doomed2:0 || fail "split-window doomed2 failed"
 $TMUX kill-window -t doomed2:0 || fail "kill-window failed"
-wait_for @log '|window-unlinked:doomed2:dwin2|session-closed:doomed2'
-assert_unchanged @log '|window-unlinked:doomed2:dwin2|session-closed:doomed2'
+wait_for @log '|session-closed:doomed2|window-unlinked:doomed2:dwin2'
+assert_unchanged @log '|session-closed:doomed2|window-unlinked:doomed2:dwin2'
 $TMUX has -t main || fail "server died after kill-window chain"
 
 # kill-session: session-closed fires first, then window-unlinked for its

regress/if-shell-error.sh

@@ -12,7 +12,8 @@ $TMUX kill-server 2>/dev/null
 
 TMP=$(mktemp)
 OUT=$(mktemp)
-trap "rm -f $TMP $OUT" 0 1 15
+trap 'rm -f "$TMP" "$OUT"; $TMUX kill-server 2>/dev/null' 0
+trap 'exit 1' 1 2 15
 
 cat <<EOF >$TMP
 if 'true' 'wibble wobble'

regress/input-common.inc

@@ -4,6 +4,9 @@ TERM=screen
 [ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
 TMUX="$TEST_TMUX -LtestA$$ -f/dev/null"
 
+# Keep panes alive until the next case or cleanup, without reading replies.
+INPUT_HOLD='while :; do sleep 3600; done'
+
 TMP=$(mktemp)
 EXP=$(mktemp)
 trap 'rm -f "$TMP" "$EXP"; $TMUX kill-server 2>/dev/null' 0 1 15
@@ -37,10 +40,10 @@ start_pane_hlimit()
 
 	$TMUX kill-server 2>/dev/null
 	sleep 0.1
-	$TMUX new-session -d -x 1 -y 1 -s test-setup "sleep 2" || exit 1
+	$TMUX new-session -d -x 1 -y 1 -s test-setup "$INPUT_HOLD" || exit 1
 	$TMUX set-option -g history-limit "$hlimit" || exit 1
 	$TMUX new-session -d -x "$sx" -y "$sy" -s "$name" \
-	    "printf '$seq'; sleep 2" || exit 1
+	    "printf '$seq'; $INPUT_HOLD" || exit 1
 	$TMUX kill-session -t test-setup
 	sleep 0.3
 }

regress/input-keys.sh

@@ -22,7 +22,19 @@ assert_key () {
 	      clear-history -t$W \; \
 	      send-keys -t$W "$key" 'EOL' || exit 1
 
-	actual_code=$($TMUX capturep -pt$W | \
+	# cat echoes the keys back asynchronously, so wait for the EOL marker
+	# to reach the pane instead of capturing straight away.
+	i=0
+	while [ $i -lt 50 ]; do
+		screen=$($TMUX capturep -pt$W)
+		case "$screen" in
+		*EOL*) break ;;
+		esac
+		i=$((i + 1))
+		sleep 0.1
+	done
+
+	actual_code=$(printf '%s\n' "$screen" | \
 			      head -1 | \
 			      sed -e 's/EOL.*$//')
 

regress/input-malformed.sh

@@ -2,6 +2,38 @@
 
 . ./input-common.inc
 
+# Wait for the terminator and following text to reach the parser.
+check_discard()
+{
+	name=$1
+	printf 'OK\n' >"$EXP"
+	i=0
+	while [ "$i" -lt 300 ]; do
+		capture_grid "$name" >"$TMP"
+		cmp -s "$TMP" "$EXP" && return 0
+		sleep 0.05
+		i=$((i + 1))
+	done
+	fail "$name (timed out waiting for discard)"
+}
+
+# The missing-terminator timer may expire before the string limit is reached
+# on a slow build. Clear any payload printed after the timeout, then check
+# that the string did not change the title and normal output has resumed.
+test_discard()
+{
+	name=$1
+	prefix=$2
+	start_cmd "$name" 8 3 "$INPUT_HOLD"
+	$TMUX select-pane -T discard-test || exit 1
+	$TMUX respawn-pane -k \
+	    "perl -e 'print qq{$prefix}, q{x} x 1100000, qq{\e\\\\\e[H\e[2JOK}'; $INPUT_HOLD" || exit 1
+	check_discard "$name"
+	$TMUX display-message -p -t "$name:" '#{pane_title}' >"$TMP" || exit 1
+	printf 'discard-test\n' >"$EXP"
+	cmp "$TMP" "$EXP" || fail "$name title"
+}
+
 start_cmd csi-param-discard 8 3 \
     "perl -e 'print qq{\e[}, q{1} x 80, qq{\030OK}'; sleep 2"
 check_capture csi-param-discard 'OK'
@@ -10,13 +42,8 @@ start_cmd csi-interm-discard 8 3 \
     "perl -e 'print qq{\e[    \030OK}'; sleep 2"
 check_capture csi-interm-discard 'OK'
 
-start_cmd osc-discard 8 3 \
-    "perl -e 'print qq{\e]2;}, q{x} x 1100000, qq{\e\\\\OK}'; sleep 2"
-check_capture osc-discard 'OK'
-
-start_cmd apc-discard 8 3 \
-    "perl -e 'print qq{\e_}, q{x} x 1100000, qq{\e\\\\OK}'; sleep 2"
-check_capture apc-discard 'OK'
+test_discard osc-discard '\e]2;'
+test_discard apc-discard '\e_'
 
 start_pane unknown-csi 8 3 '\033[?9999zOK'
 check_capture unknown-csi 'OK'

regress/input-scroll.sh

@@ -51,7 +51,7 @@ $TMUX kill-server 2>/dev/null
 sleep 0.1
 $TMUX new-session -d -x 5 -y 3 -s history \; \
     set-option -g history-limit 3 \; \
-    respawn-pane -k "printf '01\n02\n03\n04\n05\n06'; sleep 2" || exit 1
+    respawn-pane -k "printf '01\n02\n03\n04\n05\n06'; $INPUT_HOLD" || exit 1
 sleep 0.3
 $TMUX capture-pane -pN -t history: -S - -E - | normalize_capture >"$TMP"
 printf "%s\n" '01

regress/layout-custom.sh

@@ -377,10 +377,7 @@ must_equal 'Layout after select-pane back' "$(layout L:two)" "$SPLIT"
 
 # With nothing zoomed the two layout formats agree.
 #
-# The zoomed case is deliberately not covered here. While a pane is zoomed
-# #{window_layout} dumps the saved (unzoomed) layout and
-# #{window_visible_layout} the zoomed one, but that depends on how zooming
-# stashes the layout root rather than on anything in layout-custom.c.
+# Zoomed layouts are checked below with floating panes.
 must_equal 'Visible layout' "$(visible_layout L:two)" "$SPLIT"
 
 # ---------------------------------------------------------------------------
@@ -704,6 +701,42 @@ must_contain 'Floating layout back z-index' "$floating" '"z":1'
 check_ok select-layout -t L:float "$floating"
 must_equal 'Floating layout after round trip' "$(raw_layout L:float)" "$floating"
 
+# A dump taken while zoomed must retain the unzoomed floating z-indexes.
+# Check hidden floats, floats above zoom, and a mixture of the two.
+for flags in '' A mixed; do
+	check_ok new-window -d -t L: -n zoom
+	zt=$($TMUX display-message -p -t L:zoom '#{pane_id}')
+	check_ok split-window -d -h -t "$zt"
+	case "$flags" in
+	A|mixed) first=-Ad ;;
+	*) first=-d ;;
+	esac
+	case "$flags" in
+	A) second=-Ad ;;
+	*) second=-d ;;
+	esac
+	check_ok new-pane "$first" -t "$zt" -x 20 -y 6 ''
+	check_ok new-pane "$second" -t "$zt" -x 30 -y 8 ''
+	for pane in 0 2 3; do
+		check_ok select-pane -t "L:zoom.$pane"
+		before=$(raw_layout L:zoom)
+		legacy=$(v1_layout L:zoom)
+		check_ok resize-pane -Z -t "L:zoom.$pane"
+		during=$(raw_layout L:zoom)
+		must_equal 'Layout while zoomed' "$during" "$before"
+		must_equal 'Legacy layout while zoomed' \
+		    "$(v1_layout L:zoom)" "$legacy"
+		must_equal 'Zoom after dumping layout' \
+		    "$($TMUX display-message -p -t L:zoom '#{window_zoomed_flag}')" 1
+		must_differ 'Visible layout while zoomed' \
+		    "$(visible_layout L:zoom)" "$(layout L:zoom)"
+		check_ok select-layout -t L:zoom "$during"
+		must_equal 'Round trip from zoomed layout' \
+		    "$(raw_layout L:zoom)" "$before"
+	done
+	check_ok kill-window -t L:zoom
+done
+
 # ---------------------------------------------------------------------------
 # Floating panes and the legacy (v1) format.
 #

regress/modal-pane.sh

@@ -400,6 +400,107 @@ $TMUX2 send-keys -t "$OUTER" a
 sleep 1
 must_equal "$(fmt modal:0 '#{window_modal_pane}')" ''
 
+$TMUX bind P display-popup -E -t "$p0" -w 20 -h 5 -T popup-title 'cat'
+$TMUX2 send-keys -t "$OUTER" C-b P
+sleep 1
+modal=$(fmt modal:0 '#{window_modal_pane}')
+[ -n "$modal" ] || fail "display-popup did not create a modal pane"
+must_equal "$(fmt "$modal" '#{pane_title}')" popup-title
+must_equal "$($TMUX show-options -pv -t "$modal" pane-border-status)" top
+must_equal "$($TMUX show-options -pv -t "$modal" pane-border-format)" \
+	'#{pane_title}'
+$TMUX2 send-keys -t "$OUTER" C-b x z Enter
+sleep 1
+must_equal "$($TMUX show -gv @modal-prefix)" no
+must_equal "$($TMUX show -gv @modal-root)" no
+case "$($TMUX capture-pane -pt "$modal")" in
+*xz*) ;;
+*) fail "keys did not reach display-popup pane" ;;
+esac
+$TMUX2 send-keys -t "$OUTER" Escape
+sleep 1
+must_equal "$(fmt modal:0 '#{window_modal_pane}')" "$modal"
+$TMUX2 send-keys -t "$OUTER" C-c
+sleep 1
+must_equal "$(fmt modal:0 '#{window_modal_pane}')" ''
+
+# Creating a popup pane must not fire the split-window hook.
+check_ok set-hook -t modal after-split-window \
+	"set-option -g @popup-after-split yes"
+check_ok set-option -g @popup-after-split no
+check_ok display-popup -E -t "$p0" true
+must_equal "$($TMUX show-option -gv @popup-after-split)" no
+check_ok set-hook -u -t modal after-split-window
+
+# A borderless popup must not create a zero-sized pane in a tiny window.
+check_ok new-window -d -t modal: -n popup-small 'cat'
+check_ok set-option -w -t modal:popup-small window-size manual
+check_ok resize-window -t modal:popup-small -x 1 -y 1
+small=$(fmt modal:popup-small '#{pane_id}')
+check_ok bind Z display-popup -B -t "$small" 'cat'
+$TMUX2 send-keys -t "$OUTER" C-b Z
+sleep 1
+must_equal "$(fmt modal:popup-small '#{window_panes}')" 1
+must_equal "$(fmt modal:popup-small '#{window_modal_pane}')" ''
+
+$TMUX bind D display-popup -t "$p0" -w 20 -h 5 'printf done'
+$TMUX2 send-keys -t "$OUTER" C-b D
+sleep 2
+modal=$(fmt modal:0 '#{window_modal_pane}')
+[ -n "$modal" ] || fail "retained display-popup was not created"
+must_equal "$(fmt "$modal" '#{pane_dead}')" 1
+case "$($TMUX capture-pane -pt "$modal")" in
+*'Pane is dead'*) fail "display-popup showed remain-on-exit message" ;;
+esac
+$TMUX2 send-keys -t "$OUTER" a
+sleep 1
+must_equal "$(fmt modal:0 '#{window_modal_pane}')" "$modal"
+$TMUX2 send-keys -t "$OUTER" Escape
+sleep 1
+must_equal "$(fmt modal:0 '#{window_modal_pane}')" ''
+
+$TMUX bind K display-popup -k -t "$p0" -w 20 -h 5 'printf done'
+$TMUX2 send-keys -t "$OUTER" C-b K
+sleep 2
+modal=$(fmt modal:0 '#{window_modal_pane}')
+[ -n "$modal" ] || fail "display-popup -k was not created"
+must_equal "$(fmt "$modal" '#{pane_dead}')" 1
+$TMUX2 send-keys -t "$OUTER" a
+sleep 1
+must_equal "$(fmt modal:0 '#{window_modal_pane}')" ''
+
+$TMUX bind F display-popup -EE -t "$p0" -w 20 -h 5 'exit 1'
+$TMUX2 send-keys -t "$OUTER" C-b F
+sleep 2
+modal=$(fmt modal:0 '#{window_modal_pane}')
+[ -n "$modal" ] || fail "failed display-popup -EE did not remain"
+must_equal "$(fmt "$modal" '#{pane_dead}')" 1
+$TMUX2 send-keys -t "$OUTER" a
+sleep 1
+must_equal "$(fmt modal:0 '#{window_modal_pane}')" "$modal"
+$TMUX2 send-keys -t "$OUTER" Escape
+sleep 1
+must_equal "$(fmt modal:0 '#{window_modal_pane}')" "$modal"
+check_ok kill-pane -t "$modal"
+sleep 1
+
+check_ok display-popup -EE -t "$p0" true
+must_equal "$(fmt modal:0 '#{window_modal_pane}')" ''
+
+$TMUX bind G display-popup -EE -k -t "$p0" -w 20 -h 5 'exit 1'
+$TMUX2 send-keys -t "$OUTER" C-b G
+sleep 2
+modal=$(fmt modal:0 '#{window_modal_pane}')
+[ -n "$modal" ] || fail "failed display-popup -EE -k did not remain"
+must_equal "$(fmt "$modal" '#{pane_dead}')" 1
+must_equal "$($TMUX show-options -pv -t "$modal" remain-on-exit)" failed-key
+$TMUX2 send-keys -t "$OUTER" a
+sleep 1
+must_equal "$(fmt modal:0 '#{window_modal_pane}')" ''
+
+check_ok display-popup -EE -k -t "$p0" true
+must_equal "$(fmt modal:0 '#{window_modal_pane}')" ''
+
 # A nonmodal floating pane may remain above zoom, and switching between it and
 # the zoomed tiled pane must not unzoom the window.
 check_ok new-window -d -t modal: -n float-over-zoom 'cat'

regress/mode-tree-menu-position.sh

@@ -0,0 +1,71 @@
+#!/bin/sh
+
+# Chooser menus are centred on the mouse using their displayed width. A
+# hidden title must not move a borderless menu away from the mouse.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+TMUX="$TEST_TMUX -LtestA$$ -f/dev/null"
+TMUX2="$TEST_TMUX -LtestB$$ -f/dev/null"
+
+cleanup()
+{
+	$TMUX kill-server >/dev/null 2>&1
+	$TMUX2 kill-server >/dev/null 2>&1
+}
+trap cleanup 0 1 15
+
+fail()
+{
+	echo "$*" >&2
+	exit 1
+}
+
+$TMUX new-session -d -s short -x 100 -y 30 'sleep 100' || exit 1
+$TMUX set -g mouse on || exit 1
+$TMUX set -g status off || exit 1
+$TMUX2 new-session -d -x 100 -y 30 "$TMUX attach" || exit 1
+sleep 1
+
+for name in short aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa; do
+	$TMUX rename-session "$name" || exit 1
+	for lines in none single padded; do
+		$TMUX set -g menu-border-lines "$lines" || exit 1
+		$TMUX choose-tree -s || exit 1
+		sleep 1
+
+		# Right-button press at window (60, 0), away from either edge.
+		seq=$(printf '\033[<2;61;1M')
+		$TMUX2 send-keys -l "$seq" || exit 1
+		sleep 1
+
+		row=2
+		column=54
+		if [ "$lines" = none ]; then
+			row=1
+		elif [ "$name" != short ]; then
+			column=31
+		fi
+		text=$($TMUX2 capture-pane -p | awk -v row="$row" \
+		    -v column="$column" 'NR == row {
+			# Keep byte offsets equal to columns with non-Unicode awk.
+			gsub(/│/, "|")
+			print substr($0, column, 7)
+		    }')
+		[ "$text" = 'Select ' ] || \
+		    fail "$lines menu for $name: expected Select at ($column, $row), got '$text'"
+
+		# Close the menu, release the button, then leave the chooser.
+		$TMUX2 send-keys Escape || exit 1
+		seq=$(printf '\033[<2;61;1m')
+		$TMUX2 send-keys -l "$seq" || exit 1
+		$TMUX2 send-keys q || exit 1
+		sleep 1
+	done
+done
+
+exit 0

regress/mode-tree-scroll.sh

@@ -0,0 +1,168 @@
+#!/bin/sh
+
+# Tests that the scroll position of a mode tree list (mode-tree.c) is kept
+# when the list is rebuilt, using choose-buffer. Buffer mode rebuilds its list
+# every time the status line is redrawn, which used to move the view so the
+# selected line was on the bottom row (or the list jumped back to the top)
+# even if the selected line was already visible. Also checks that when the
+# list shrinks the view does not leave empty lines at the bottom.
+#
+# The list is drawn on a mode screen which capture-pane does not show, so - as
+# in choose-buffer.sh - a second server provides a client: an inner "tmux
+# attach" runs inside a pane of the second server, and that pane is captured
+# to read what the inner client rendered.
+
+PATH=/bin:/usr/bin
+TERM=screen
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+TMP=$(mktemp -d) || exit 1
+TMUX_TMPDIR="$TMP"
+export TMUX_TMPDIR
+TMUX="$TEST_TMUX -LtestA$$ -f/dev/null"
+TMUX2="$TEST_TMUX -LtestB$$ -f/dev/null"
+
+cleanup()
+{
+	$TMUX kill-server 2>/dev/null
+	$TMUX2 kill-server 2>/dev/null
+	rm -rf "$TMP"
+}
+trap cleanup EXIT
+
+fail()
+{
+	echo "$1" >&2
+	exit 1
+}
+
+# capture the screen rendered by the inner client
+capture()
+{
+	$TMUX2 capture-pane -p -t out:0 2>/dev/null
+}
+
+# wait_for $marker
+#
+# Wait (up to ~10s) until the rendered screen contains $marker. The matching
+# capture is left in CAPTURED.
+wait_for()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		CAPTURED=$(capture)
+		if printf '%s\n' "$CAPTURED" | grep -F -q "$1"; then
+			return 0
+		fi
+		sleep 0.2
+		i=$((i + 1))
+	done
+	fail "timed out waiting for '$1'"
+}
+
+# wait_gone $marker
+#
+# Wait (up to ~10s) until the rendered screen no longer contains $marker. The
+# matching capture is left in CAPTURED.
+wait_gone()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		CAPTURED=$(capture)
+		if ! printf '%s\n' "$CAPTURED" | grep -F -q "$1"; then
+			return 0
+		fi
+		sleep 0.2
+		i=$((i + 1))
+	done
+	fail "timed out waiting for '$1' to disappear"
+}
+
+# wait_clients $n
+#
+# Wait (up to ~10s) until the test server has exactly $n clients attached.
+wait_clients()
+{
+	i=0
+	while [ "$i" -lt 10 ]; do
+		c=$($TMUX list-clients -F x 2>/dev/null | grep -c x)
+		[ "$c" -eq "$1" ] && return 0
+		sleep 1
+		i=$((i + 1))
+	done
+	return 1
+}
+
+# first_line
+#
+# Print the name of the first buffer shown in CAPTURED.
+first_line()
+{
+	printf '%s\n' "$CAPTURED" | grep -F ': S1' | head -1 | \
+	    sed 's/.*\(buf[0-9a-z]*\): S1.*/\1/'
+}
+
+$TMUX new-session -d -s aaa -x 80 -y 24 'cat' || exit 1
+
+$TMUX2 new-session -d -s out -x 80 -y 24 "$TMUX attach -t aaa" || exit 1
+wait_clients 1 || fail "no client attached to test server"
+
+# Forty buffers, more than fit on the screen.
+n=0
+while [ "$n" -lt 40 ]; do
+	$TMUX set-buffer -b "$(printf 'buf%02d' "$n")" "buffer $n" || exit 1
+	n=$((n + 1))
+done
+
+# Without a preview the list has the whole pane (23 lines with the status
+# line), so buf00 to buf22 are visible.
+$TMUX choose-buffer -t aaa:0 -N -O name -F 'S1' || exit 1
+wait_for 'buf00: S1'
+
+# --- scrolling down moves the view -------------------------------------------
+#
+# Selecting buf30 scrolls so it is on the bottom row: buf08 is at the top.
+$TMUX send-keys -t aaa:0 -N 30 Down || exit 1
+wait_for 'buf30: S1'
+top=$(first_line)
+[ "$top" = "buf08" ] || fail "top line after scrolling is $top, not buf08"
+
+# Moving up to buf20 stays inside the visible lines so the view does not move.
+$TMUX send-keys -t aaa:0 -N 10 Up || exit 1
+
+# --- a rebuild keeps the view where it is ------------------------------------
+#
+# Add a buffer that sorts into the visible part of the list and redraw the
+# status line so the list is rebuilt. Once buf15a appears the rebuild has
+# happened; buf08 must still be the top line. It used to jump back to buf00.
+$TMUX set-buffer -b buf15a "new buffer" || exit 1
+$TMUX refresh-client -S || exit 1
+wait_for 'buf15a: S1'
+top=$(first_line)
+[ "$top" = "buf08" ] || fail "top line after rebuild is $top, not buf08"
+
+# --- a shrinking list does not leave empty lines -----------------------------
+#
+# Go to the end of the list (buf39 is on the bottom row) and delete all but
+# the last ten buffers. They now all fit, so the view goes to the top.
+$TMUX send-keys -t aaa:0 End || exit 1
+wait_for 'buf39: S1'
+for b in $($TMUX list-buffers -F '#{buffer_name}'); do
+	case "$b" in
+	buf3?)
+		;;
+	*)
+		$TMUX delete-buffer -b "$b" || exit 1
+		;;
+	esac
+done
+$TMUX refresh-client -S || exit 1
+wait_gone 'buf29: S1'
+top=$(first_line)
+[ "$top" = "buf30" ] || fail "top line after shrinking is $top, not buf30"
+[ "$(printf '%s\n' "$CAPTURED" | grep -F -c ': S1')" -eq 10 ] || \
+	fail "expected 10 buffers after shrinking"
+
+$TMUX send-keys -t aaa:0 q
+
+exit 0

regress/popup-drag-wide-character.sh

@@ -0,0 +1,126 @@
+#!/bin/sh
+
+# Damage at a popup edge must redraw complete grid characters. Drawing only a
+# wide character's base or padding cell leaves a two-cell hole behind.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+INNER="$TEST_TMUX -Lpopup-wide-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Lpopup-wide-outer-$$ -f/dev/null"
+EMITTER=$DIR/emitter.pl
+BASE=$DIR/base
+CAPTURE=$DIR/capture
+POPUP_PID=
+
+fail()
+{
+	echo "$*" >&2
+	[ -s "$CAPTURE" ] && cat "$CAPTURE" >&2
+	exit 1
+}
+
+cleanup()
+{
+	[ -n "$POPUP_PID" ] && kill "$POPUP_PID" 2>/dev/null
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+wait_for_client()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		CLIENT=$($INNER list-clients -F '#{client_name}' 2>/dev/null)
+		[ -n "$CLIENT" ] && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "inner client did not attach"
+}
+
+wait_outer_has()
+{
+	marker=$1
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t outer:0.0 >"$CAPTURE" 2>/dev/null || true
+		grep -q "$marker" "$CAPTURE" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "outer client did not show $marker"
+}
+
+wait_old_rows_restored()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t outer:0.0 >"$CAPTURE" 2>/dev/null || true
+		sed -n '3,5p' "$BASE" >"$DIR/want"
+		sed -n '3,5p' "$CAPTURE" >"$DIR/got"
+		cmp -s "$DIR/want" "$DIR/got" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "wide characters under the old popup edge were not restored"
+}
+
+mouse()
+{
+	sequence=$(printf '\033[<%s;%s;%s%s' "$1" "$2" "$3" "$4")
+	$OUTER send-keys -t outer:0.0 -l "$sequence" || exit 1
+	sleep 0.1
+}
+
+cat >"$EMITTER" <<'PERL'
+use strict;
+use warnings;
+
+binmode STDOUT, ':encoding(UTF-8)';
+$| = 1;
+for my $row (1 .. 10) {
+	print "\e[$row;1H", chr(0x754c) x 20;
+}
+sleep 100;
+PERL
+
+$INNER new-session -d -s inner -x 40 -y 10 "perl '$EMITTER'" || exit 1
+$INNER set-option -g status off || exit 1
+$INNER set-option -g window-size manual || exit 1
+$INNER set-option -g mouse on || exit 1
+
+$OUTER new-session -d -s outer -x 40 -y 10 'sleep 100' || exit 1
+$OUTER set-option -g status off || exit 1
+$OUTER set-option -g window-size manual || exit 1
+$OUTER set-option -g default-terminal screen-256color || exit 1
+$OUTER respawn-pane -k -t outer:0.0 \
+    "$TEST_TMUX -Lpopup-wide-inner-$$ -f/dev/null attach-session -t inner" ||
+    exit 1
+
+wait_for_client
+wait_outer_has '界界界'
+$OUTER capture-pane -p -t outer:0.0 >"$BASE" || exit 1
+
+$INNER display-popup -t "$CLIENT" -x 5 -y 5 -w 10 -h 3 -E \
+    "sh -c 'printf POPUP; exec sleep 100'" &
+POPUP_PID=$!
+wait_outer_has POPUP
+
+# The first motion starts the drag; the second moves the popup away from its
+# old rectangle. Its odd x coordinate bisects the underlying double-width
+# cells at both edges.
+mouse 0 10 3 M
+mouse 32 11 3 M
+mouse 32 28 7 M
+mouse 0 28 7 m
+wait_old_rows_restored
+
+exit 0

regress/prompt-words-history.sh

@@ -131,6 +131,14 @@ printf '%s\n' "$captured" | grep -Fq 'show-buffer' ||
 printf '%s\n' "$captured" | grep -Fq 'show-environment' ||
 	fail "ambiguous completion list was incomplete"
 $OUTER send-keys Escape || exit 1
+# Wait until Escape has closed the prompt before sending another Meta key.
+# Otherwise the two can be parsed together as a single escape sequence.
+i=0
+while capture | grep -Fq '(word)'; do
+	[ "$i" -lt 50 ] || fail "completion prompt did not close"
+	sleep 0.1
+	i=$((i + 1))
+done
 
 # Add entries to both history rings through real prompts.
 bind_prompt 'history-command'

regress/redraw-damage-accumulate.sh

@@ -0,0 +1,113 @@
+#!/bin/sh
+
+# Many wrapped rows crossing a panned viewport produce disjoint damage.
+# Every row must survive the rectangle-count limit and subsequent merging.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+DIR=$(mktemp -d) || exit 1
+INNER="$TEST_TMUX -Laccumulate-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Laccumulate-outer-$$ -f/dev/null"
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+fail()
+{
+	echo "$*" >&2
+	exit 1
+}
+wait_marker()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t outer:0.0 >"$DIR/capture" || exit 1
+		grep -q "$1" "$DIR/capture" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "client did not receive $1"
+}
+cat >"$DIR/emitter.pl" <<'PERL'
+use strict;
+use warnings;
+$| = 1;
+for my $row (1 .. 80) {
+	printf "\e[%d;1HROW%02d-%s", $row, $row, 'abcdefghij' x 6;
+}
+print "\e[1;1H";
+while (!-e $ENV{TRIGGER}) {
+	select undef, undef, undef, 0.01;
+}
+my $output = '';
+# Each wrapped second row needs a separate damage rectangle. Keep the
+# batch below the PTY read size so all 18 arrive in the same input pass.
+for my $region (0 .. 17) {
+	my $top = 1 + $region * 4;
+	$output .= "\e[$top;1H" . ('A' x 80) . ('B' x 24) .
+	    sprintf('DAMAGE%02d', $region) . ('B' x 48);
+}
+$output .= "\e[80;21HDONE";
+syswrite STDOUT, $output;
+while (!-e "$ENV{TRIGGER}-merge") {
+	select undef, undef, undef, 0.01;
+}
+# Returning from the alternate screen requests a full-pane rectangle. A
+# later wrapped-row rectangle overlaps it and must not shrink that damage.
+$output = "\e[?1049h\e[40;21HALT-VISIBLE\e[?1049l";
+$output .= "\e[1;1H" . ('C' x 80) . ('D' x 24) . 'MERGE00' . ('D' x 49);
+$output .= "\e[80;21HMERGED";
+syswrite STDOUT, $output;
+sleep 100;
+PERL
+$INNER new-session -d -s inner -x 80 -y 80 \
+    "TRIGGER='$DIR/trigger' perl '$DIR/emitter.pl'" || exit 1
+$INNER set -g status off || exit 1
+$INNER set -g window-size manual || exit 1
+$INNER set -g automatic-rename off || exit 1
+$INNER set -g status-interval 0 || exit 1
+$INNER set -as terminal-features ',screen:sync' || exit 1
+$INNER set -g pane-border-lines simple || exit 1
+$OUTER new-session -d -s outer -x 40 -y 80 'sleep 100' || exit 1
+$OUTER set -g status off || exit 1
+$OUTER set -g window-size manual || exit 1
+$OUTER set -g default-terminal screen || exit 1
+$OUTER respawn-pane -k -t outer:0.0 "$INNER attach -t inner" || exit 1
+wait_marker ROW80
+CLIENT=$($OUTER display -p -t outer:0.0 '#{pane_tty}') || exit 1
+$INNER refresh-client -t "$CLIENT" -R 20 || exit 1
+# Keep the emitter inactive so its writes use a synchronized frame. Otherwise
+# its own queued output can force a full redraw and hide lost rectangles.
+$INNER new-pane -x 6 -y 3 -X 65 -Y 74 'sleep 100' || exit 1
+sleep 0.2
+: >"$DIR/trigger"
+wait_marker DONE
+sleep 0.2
+$OUTER capture-pane -p -t outer:0.0 >"$DIR/before" || exit 1
+region=0
+while [ "$region" -lt 18 ]; do
+	marker=$(printf 'DAMAGE%02d' "$region")
+	sed -n "$((2 + region * 4))p" "$DIR/before" | grep -q "$marker" ||
+	    fail "missing damage for region $region"
+	region=$((region + 1))
+done
+$INNER refresh-client -t "$CLIENT" || exit 1
+sleep 0.2
+$OUTER capture-pane -p -t outer:0.0 >"$DIR/after" || exit 1
+diff -u "$DIR/before" "$DIR/after" || fail "accumulated redraw differs from full redraw"
+: >"$DIR/trigger-merge"
+wait_marker MERGED
+sleep 0.2
+$OUTER capture-pane -p -t outer:0.0 >"$DIR/before" || exit 1
+sed -n '2p' "$DIR/before" | grep -q MERGE00 || fail "merged damage lost the wrapped row"
+$INNER refresh-client -t "$CLIENT" || exit 1
+sleep 0.2
+$OUTER capture-pane -p -t outer:0.0 >"$DIR/after" || exit 1
+diff -u "$DIR/before" "$DIR/after" || fail "merged redraw differs from full redraw"
+exit 0

regress/redraw-damage-blocked-client.sh

@@ -0,0 +1,140 @@
+#!/bin/sh
+
+# One terminal stops reading while another consumes floating-pane damage.
+# The slow client must catch up after the window's shared damage is cleared.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+DIR=$(mktemp -d) || exit 1
+INNER="$TEST_TMUX -Lblocked-inner-$$ -f/dev/null"
+FAST="$TEST_TMUX -Lblocked-fast-$$ -f/dev/null"
+SLOW="$TEST_TMUX -Lblocked-slow-$$ -f/dev/null"
+STOPPED=
+cleanup()
+{
+	[ -n "$STOPPED" ] && kill -CONT "$STOPPED" 2>/dev/null
+	$FAST kill-server 2>/dev/null
+	$SLOW kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+fail()
+{
+	echo "$*" >&2
+	exit 1
+}
+wait_marker()
+{
+	terminal=$1
+	marker=$2
+	i=0
+	while [ "$i" -lt 100 ]; do
+		$terminal capture-pane -p >"$DIR/capture" || exit 1
+		grep -q "$marker" "$DIR/capture" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "client did not receive $marker"
+}
+mouse()
+{
+	sequence=$(printf '\033[<%s;%s;%s%s' "$1" "$2" "$3" "$4")
+	$FAST send-keys -l "$sequence" || exit 1
+	sleep 0.2
+}
+cat >"$DIR/emitter.pl" <<'PERL'
+use strict;
+use warnings;
+$| = 1;
+print 'READY';
+while (!-e "$ENV{TRIGGER}-flood") {
+	select undef, undef, undef, 0.01;
+}
+my $frame = 0;
+while (!-e "$ENV{TRIGGER}-stop") {
+	my $output = '';
+	for my $row (1 .. 20) {
+		$output .= "\e[$row;1H" . join('', map { chr(33 + ($_ + $frame) % 80) } 0 .. 77);
+	}
+	print $output;
+	$frame++;
+	select undef, undef, undef, 0.01;
+}
+for my $row (1 .. 20) {
+	printf "\e[%d;1HFINAL%02d-%s", $row, $row, '0123456789' x 7;
+}
+print "\e[20;1HDONE";
+sleep 100;
+PERL
+$INNER new-session -d -s inner -x 160 -y 80 \
+    "TRIGGER='$DIR/trigger' perl '$DIR/emitter.pl'" || exit 1
+$INNER set -g status off || exit 1
+$INNER set -g window-size manual || exit 1
+$INNER set -g automatic-rename off || exit 1
+$INNER set -g status-interval 0 || exit 1
+$INNER set -g mouse on || exit 1
+$INNER set -g pane-border-lines simple || exit 1
+FLOAT=$($INNER new-pane -PF '#{pane_id}' -x 16 -y 5 -X 5 -Y 5 \
+    'printf FLOAT; exec sleep 100') || exit 1
+for terminal in "$FAST" "$SLOW"; do
+	$terminal new-session -d -x 160 -y 80 'sleep 100' || exit 1
+	$terminal set -g status off || exit 1
+	$terminal set -g window-size manual || exit 1
+	$terminal set -g default-terminal screen || exit 1
+	$terminal respawn-pane -k "$INNER attach -t inner" || exit 1
+	wait_marker "$terminal" READY
+done
+FASTCLIENT=$($FAST display -p '#{pane_tty}') || exit 1
+SLOWCLIENT=$($SLOW display -p '#{pane_tty}') || exit 1
+SLOWPID=$($SLOW display -p '#{pid}') || exit 1
+before=$($INNER display -p -c "$FASTCLIENT" '#{client_written}') || exit 1
+slowbefore=$($INNER display -p -c "$SLOWCLIENT" '#{client_written}') || exit 1
+# The large terminal keeps this backlog below the discard threshold, so
+# automatic recovery from discarded output cannot mask lost damage.
+# Stop only our outer server, leaving its inner client attached to a PTY
+# whose master is no longer read. This creates real terminal backpressure.
+STOPPED=$SLOWPID
+kill -STOP "$SLOWPID" || exit 1
+: >"$DIR/trigger-flood"
+i=0
+while :; do
+	written=$($INNER display -p -c "$SLOWCLIENT" '#{client_written}') || exit 1
+	fastwritten=$($INNER display -p -c "$FASTCLIENT" '#{client_written}') || exit 1
+	# More than a PTY can buffer has been queued for the stopped terminal,
+	# while the other terminal is still receiving the same output.
+	[ "$written" -gt "$((slowbefore + 65536))" ] &&
+	    [ "$fastwritten" -gt "$((before + 65536))" ] && break
+	[ "$i" -lt 100 ] || fail "slow client did not become blocked"
+	sleep 0.1
+	i=$((i + 1))
+done
+: >"$DIR/trigger-stop"
+wait_marker "$FAST" DONE
+[ "$($INNER display -p -c "$FASTCLIENT" '#{client_discarded}')" -eq 0 ] ||
+    fail "fast client also became blocked"
+mouse 0 12 6 M
+mouse 32 42 6 M
+mouse 0 42 6 m
+[ "$($INNER display -p -t "$FLOAT" '#{pane_left}')" -eq 36 ] || fail "pane did not move"
+$FAST capture-pane -p >"$DIR/fast-before" || exit 1
+# Ensure the fast client already restored the vacated frame.
+sed -n '6p' "$DIR/fast-before" | grep -q '^FINAL06-0123456789' ||
+    fail "fast client did not restore old footprint"
+kill -CONT "$SLOWPID" || exit 1
+STOPPED=
+wait_marker "$SLOW" DONE
+# Allow queued terminal output and deferred redraws to drain.
+sleep 0.5
+[ "$($INNER display -p -c "$SLOWCLIENT" '#{client_discarded}')" -eq 0 ] ||
+    fail "discard recovery could mask lost deferred damage"
+$SLOW capture-pane -p >"$DIR/slow-before" || exit 1
+diff -u "$DIR/fast-before" "$DIR/slow-before" || fail "slow client did not catch up"
+$INNER refresh-client -t "$FASTCLIENT" || exit 1
+sleep 0.2
+$FAST capture-pane -p >"$DIR/after" || exit 1
+diff -u "$DIR/fast-before" "$DIR/after" || fail "damage redraw differed from full redraw"
+exit 0

regress/redraw-damage-only.sh

@@ -0,0 +1,112 @@
+#!/bin/sh
+
+# Check a redraw callback which has no accompanying client redraw flags. A
+# wrapped row crossing a panned viewport cannot use the direct tty path.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+INNER="$TEST_TMUX -Ldamage-only-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Ldamage-only-outer-$$ -f/dev/null"
+EMITTER=$DIR/emitter.pl
+TRIGGER=$DIR/trigger
+CAPTURE=$DIR/capture
+
+fail()
+{
+	echo "$*" >&2
+	[ -s "$CAPTURE" ] && cat "$CAPTURE" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+wait_for_client()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		CLIENT=$($INNER list-clients -F '#{client_name}' 2>/dev/null)
+		[ -n "$CLIENT" ] && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "inner client did not attach"
+}
+
+wait_outer_has()
+{
+	marker=$1
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t outer:0.0 >"$CAPTURE" 2>/dev/null || true
+		grep -q "$marker" "$CAPTURE" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "outer client did not show $marker"
+}
+
+wait_inner_has()
+{
+	marker=$1
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$INNER capture-pane -p -t inner:0.0 2>/dev/null |
+		    grep -q "$marker" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "inner pane did not contain $marker"
+}
+
+cat >"$EMITTER" <<'PERL'
+use strict;
+use warnings;
+
+$| = 1;
+for my $row (1 .. 12) {
+	print "\e[$row;1H", 'o' x 79;
+}
+print "\e[1;1H";
+while (!-e $ENV{TRIGGER}) {
+	select undef, undef, undef, 0.01;
+}
+
+my $second = ('B' x 24) . 'DAMAGE-ONLY' . ('B' x 45);
+print "\e[5;1H", ('A' x 80), $second;
+sleep 100;
+PERL
+
+$INNER new-session -d -s inner -x 80 -y 12 \
+    "TRIGGER='$TRIGGER' perl '$EMITTER'" || exit 1
+$INNER set-option -g status off || exit 1
+$INNER set-option -g window-size manual || exit 1
+
+$OUTER new-session -d -s outer -x 40 -y 12 'sleep 100' || exit 1
+$OUTER set-option -g status off || exit 1
+$OUTER set-option -g window-size manual || exit 1
+$OUTER set-option -g default-terminal screen || exit 1
+$OUTER respawn-pane -k -t outer:0.0 \
+    "$TEST_TMUX -Ldamage-only-inner-$$ -f/dev/null attach-session -t inner" ||
+    exit 1
+
+wait_for_client
+$INNER refresh-client -t "$CLIENT" -R 20 || exit 1
+wait_outer_has oooooooooo
+
+: >"$TRIGGER"
+wait_inner_has DAMAGE-ONLY
+wait_outer_has DAMAGE-ONLY
+
+exit 0

regress/redraw-damage-viewports.sh

@@ -0,0 +1,112 @@
+#!/bin/sh
+
+# Moving and interactively resizing floating panes must restore both clients,
+# including a smaller client panned horizontally and vertically.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+DIR=$(mktemp -d) || exit 1
+INNER="$TEST_TMUX -Lviewports-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Lviewports-outer-$$ -f/dev/null"
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+fail()
+{
+	echo "$*" >&2
+	exit 1
+}
+mouse()
+{
+	sequence=$(printf '\033[<%s;%s;%s%s' "$1" "$2" "$3" "$4")
+	$OUTER send-keys -t wide:0.0 -l "$sequence" || exit 1
+	sleep 0.2
+}
+assert_scene()
+{
+	# Compare what each terminal actually received with a fresh full redraw.
+	# Capture both first: refreshing one client must not repair the other.
+	for target in wide small; do
+		$OUTER capture-pane -p -t "$target:0.0" >"$DIR/$target-before" || exit 1
+	done
+	$INNER refresh-client -t "$WIDE" || exit 1
+	$INNER refresh-client -t "$SMALL" || exit 1
+	sleep 0.2
+	for target in wide small; do
+		$OUTER capture-pane -p -t "$target:0.0" >"$DIR/$target-after" || exit 1
+		diff -u "$DIR/$target-before" "$DIR/$target-after" ||
+		    fail "$1: $target client differed from a full redraw"
+	done
+}
+
+cat >"$DIR/background.pl" <<'PERL'
+$| = 1;
+for my $row (1 .. 24) {
+	printf "\e[%d;1HROW%02d-", $row, $row;
+	print '0123456789' x 7;
+}
+sleep 100;
+PERL
+$INNER new-session -d -s inner -x 80 -y 24 "perl '$DIR/background.pl'" || exit 1
+$INNER set -g status off || exit 1
+$INNER set -g window-size manual || exit 1
+$INNER set -g automatic-rename off || exit 1
+$INNER set -g status-interval 0 || exit 1
+$INNER set -g mouse on || exit 1
+$INNER set -g default-command 'sleep 100' || exit 1
+$INNER set -g pane-border-lines simple || exit 1
+$OUTER new-session -d -s wide -x 80 -y 24 'sleep 100' || exit 1
+$OUTER set -g status off || exit 1
+$OUTER set -g window-size manual || exit 1
+$OUTER set -g default-terminal screen || exit 1
+$OUTER new-session -d -s small -x 40 -y 12 'sleep 100' || exit 1
+for target in wide small; do
+	$OUTER respawn-pane -k -t "$target:0.0" "$INNER attach -t inner" || exit 1
+done
+i=0
+while [ "$($INNER list-clients | wc -l)" -ne 2 ]; do
+	[ "$i" -lt 50 ] || fail "two clients did not attach"
+	sleep 0.1
+	i=$((i + 1))
+done
+WIDE=$($OUTER display -p -t wide:0.0 '#{pane_tty}') || exit 1
+SMALL=$($OUTER display -p -t small:0.0 '#{pane_tty}') || exit 1
+$INNER refresh-client -t "$SMALL" -R 20 || exit 1
+$INNER refresh-client -t "$SMALL" -D 6 || exit 1
+FLOAT=$($INNER new-pane -d -PF '#{pane_id}' -x 16 -y 6 -X 25 -Y 9) || exit 1
+sleep 0.3
+assert_scene initial
+# Confirm that the two clients really have different viewports.
+[ "$(head -1 "$DIR/wide-before" | cut -c1-6)" = ROW01- ] || fail "wrong wide viewport"
+[ "$(head -1 "$DIR/small-before" | cut -c1-6)" != ROW01- ] || fail "small client was not panned"
+
+# Meta-drag the body using move-pane -M, including a partially clipped position.
+mouse 8 30 12 M
+mouse 40 48 15 M
+[ "$($INNER display -p -t "$FLOAT" '#{pane_left}')" -eq 44 ] || fail "Meta-drag did not move pane"
+assert_scene move-right
+mouse 40 28 10 M
+assert_scene move-back
+mouse 8 28 10 m
+
+# Ctrl-drag creates a new floating pane, then changes its size while held.
+mouse 16 52 14 M
+mouse 48 75 23 M
+NEW=$($INNER display -p '#{pane_id}') || exit 1
+[ "$NEW" != "$FLOAT" ] || fail "Ctrl-drag did not create a pane"
+[ "$($INNER display -p -t "$NEW" '#{pane_floating_flag}')" -eq 1 ] || fail "new pane is not floating"
+assert_scene create
+mouse 48 64 19 M
+[ "$($INNER display -p -t "$NEW" '#{pane_width}')" -eq 11 ] || fail "Ctrl-drag did not shrink pane"
+assert_scene shrink
+mouse 16 64 19 m
+assert_scene release
+exit 0

regress/redraw-multiclient.sh

@@ -0,0 +1,186 @@
+#!/bin/sh
+
+# Redraw a moved floating pane on both attached clients viewing the same
+# window. Window redraw work must not be consumed by only one client.
+#
+# Uses ASCII pane borders (rather than the default UTF-8 box-drawing) because
+# this test nests a real tmux client inside another tmux's pane to get a
+# genuine terminal to capture from; that nested-tmux relay has been observed
+# to mis-render a cell that previously held a multi-byte UTF-8 border
+# character being overwritten later by plain content, on the outer instance's
+# own interpretation, independent of anything the inner tmux sends. That is a
+# nested-test-harness artifact, not a real tmux bug - confirmed by replaying
+# the exact same drag sequence against a real terminal (xterm), where it
+# never reproduces. ASCII borders avoid the artifact entirely.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+INNER="$TEST_TMUX -Lredraw-multi-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Lredraw-multi-outer-$$ -f/dev/null"
+CAPTURE=$DIR/capture
+
+fail()
+{
+	echo "$*" >&2
+	[ -s "$CAPTURE" ] && cat "$CAPTURE" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+wait_for_clients()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		count=$($INNER list-clients 2>/dev/null | wc -l)
+		[ "$count" -eq 2 ] && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "two inner clients did not attach"
+}
+
+wait_outer_has()
+{
+	target=$1
+	marker=$2
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t "$target" >"$CAPTURE" 2>/dev/null || true
+		grep -q "$marker" "$CAPTURE" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "outer pane $target did not show $marker"
+}
+
+wait_float_left()
+{
+	comparison=$1
+	limit=$2
+	i=0
+	while [ "$i" -lt 50 ]; do
+		left=$($INNER display-message -p -t "$FLOAT" '#{pane_left}')
+		if [ "$comparison" = gt ] && [ "$left" -gt "$limit" ]; then
+			return 0
+		fi
+		if [ "$comparison" = lt ] && [ "$left" -lt "$limit" ]; then
+			return 0
+		fi
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "floating pane did not move"
+}
+
+mouse()
+{
+	sequence=$(printf '\033[<%s;%s;%s%s' "$2" "$3" "$4" "$5")
+	$OUTER send-keys -t "$1" -l "$sequence" || exit 1
+	sleep 0.1
+}
+
+drag_float()
+{
+	target=$1
+	startcol=$2
+	startrow=$3
+	endcol=$4
+	mouse "$target" 0 "$startcol" "$startrow" M
+	mouse "$target" 32 "$endcol" "$startrow" M
+	mouse "$target" 0 "$endcol" "$startrow" m
+}
+
+assert_scene()
+{
+	target=$1
+	base=$2
+	firstcol=$3
+	lastcol=$4
+
+	$OUTER capture-pane -p -t "$target" >"$CAPTURE" || exit 1
+
+	# With ASCII (simple) borders every corner and junction is the same
+	# '+', so one rectangular floating pane always draws exactly 4 of
+	# them; more means a stale frame was left behind somewhere.
+	corners=$(grep -o '+' "$CAPTURE" | wc -l)
+	[ "$corners" -eq 4 ] ||
+	    fail "outer pane $target had $corners floating frames"
+
+	sed -n '6,11p' "$base" | cut -c"$firstcol-$lastcol" >"$DIR/want"
+	sed -n '6,11p' "$CAPTURE" | cut -c"$firstcol-$lastcol" >"$DIR/got"
+	cmp -s "$DIR/want" "$DIR/got" ||
+	    fail "outer pane $target did not restore the old floating area"
+}
+
+C="sh -c 'i=0; while [ \$i -lt 20 ]; do printf \"\\033[%d;1HBG-ROW-%02d-abcdefghijklmnopqrstuvwxyz0123456789\" \$((i + 1)) \$i; i=\$((i + 1)); done; exec sleep 100'"
+
+$INNER new-session -d -s inner -x 60 -y 20 "$C" || exit 1
+$INNER set-option -g status off || exit 1
+$INNER set-option -g window-size manual || exit 1
+$INNER set-option -g mouse on || exit 1
+$INNER set-option -g default-command 'sleep 100' || exit 1
+$INNER set-option -g pane-border-lines simple || exit 1
+
+$OUTER new-session -d -s outer -x 121 -y 20 'sleep 100' || exit 1
+$OUTER set-option -g status off || exit 1
+$OUTER set-option -g window-size manual || exit 1
+$OUTER set-option -g default-terminal screen || exit 1
+$OUTER split-window -h -t outer:0.0 'sleep 100' || exit 1
+
+PANES=$($OUTER list-panes -t outer:0 -F '#{pane_id} #{pane_left}')
+LEFT=$(echo "$PANES" | sort -k2 -n | head -1 | cut -d' ' -f1)
+RIGHT=$(echo "$PANES" | sort -k2 -n | tail -1 | cut -d' ' -f1)
+[ -n "$LEFT" ] && [ -n "$RIGHT" ] || fail "could not find outer panes"
+
+$OUTER respawn-pane -k -t "$LEFT" \
+    "$TEST_TMUX -Lredraw-multi-inner-$$ -f/dev/null attach-session -t inner" ||
+    exit 1
+$OUTER respawn-pane -k -t "$RIGHT" \
+    "$TEST_TMUX -Lredraw-multi-inner-$$ -f/dev/null attach-session -t inner" ||
+    exit 1
+
+wait_for_clients
+wait_outer_has "$LEFT" BG-ROW-19
+wait_outer_has "$RIGHT" BG-ROW-19
+$OUTER capture-pane -p -t "$LEFT" >"$DIR/base-left" || exit 1
+$OUTER capture-pane -p -t "$RIGHT" >"$DIR/base-right" || exit 1
+
+FLOAT=$($INNER new-pane -dPF '#{pane_id}' -x 16 -y 5 -X 5 -Y 5) ||
+    fail "could not create floating pane"
+wait_outer_has "$LEFT" '+'
+wait_outer_has "$RIGHT" '+'
+
+FTOP=$($INNER display-message -p -t "$FLOAT" '#{pane_top}')
+FLEFT=$($INNER display-message -p -t "$FLOAT" '#{pane_left}')
+FWIDTH=$($INNER display-message -p -t "$FLOAT" '#{pane_width}')
+GRABCOL=$((FLEFT + FWIDTH / 2 + 1))
+
+# Move right through one client and require both clients to restore the old
+# left-hand footprint.
+drag_float "$LEFT" "$GRABCOL" "$FTOP" $((GRABCOL + 30))
+wait_float_left gt 30
+assert_scene "$LEFT" "$DIR/base-left" 1 20
+assert_scene "$RIGHT" "$DIR/base-right" 1 20
+
+# Move back through the other client and check the old right-hand footprint.
+FLEFT=$($INNER display-message -p -t "$FLOAT" '#{pane_left}')
+GRABCOL=$((FLEFT + FWIDTH / 2 + 1))
+drag_float "$RIGHT" "$GRABCOL" "$FTOP" $((GRABCOL - 30))
+wait_float_left lt 10
+assert_scene "$LEFT" "$DIR/base-left" 35 60
+assert_scene "$RIGHT" "$DIR/base-right" 35 60
+
+exit 0

regress/redraw-screen-write.sh

@@ -0,0 +1,208 @@
+#!/bin/sh
+
+# Check that full and region screen-write fallbacks update an attached client,
+# not only tmux's internal pane grid.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+EMITTER=$DIR/emitter.pl
+CAPTURE=$DIR/capture
+INNER=
+OUTER=
+N=0
+
+fail()
+{
+	echo "$*" >&2
+	[ -s "$CAPTURE" ] && cat "$CAPTURE" >&2
+	exit 1
+}
+
+cleanup()
+{
+	[ -n "$OUTER" ] && $OUTER kill-server 2>/dev/null
+	[ -n "$INNER" ] && $INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+wait_outer_has()
+{
+	marker=$1
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t outer:0.0 >"$CAPTURE" 2>/dev/null || true
+		grep -q "$marker" "$CAPTURE" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "outer client did not show $marker"
+}
+
+wait_outer_lacks()
+{
+	marker=$1
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t outer:0.0 >"$CAPTURE" 2>/dev/null || true
+		grep -q "$marker" "$CAPTURE" || return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "outer client still showed $marker"
+}
+
+wait_inner_has()
+{
+	marker=$1
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$INNER capture-pane -p -t inner:0.0 2>/dev/null |
+		    grep -q "$marker" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "inner pane did not contain $marker"
+}
+
+wait_inner_lacks()
+{
+	marker=$1
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$INNER capture-pane -p -t inner:0.0 >"$CAPTURE" 2>/dev/null || true
+		grep -q "$marker" "$CAPTURE" || return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "inner pane still contained $marker"
+}
+
+setup()
+{
+	mode=$1
+	[ -n "$OUTER" ] && $OUTER kill-server 2>/dev/null
+	[ -n "$INNER" ] && $INNER kill-server 2>/dev/null
+	N=$((N + 1))
+	INNER="$TEST_TMUX -Lredraw-write-inner-$$-$N -f/dev/null"
+	OUTER="$TEST_TMUX -Lredraw-write-outer-$$-$N -f/dev/null"
+
+	$INNER new-session -d -s inner -x 40 -y 12 \
+	    "MODE=$mode READY='$DIR/ready-$N' TRIGGER='$DIR/trigger-$N' perl '$EMITTER'" ||
+	    exit 1
+	$INNER set-option -g status off || exit 1
+	$INNER set-option -g window-size manual || exit 1
+
+	$OUTER new-session -d -s outer -x 40 -y 12 'sleep 100' || exit 1
+	$OUTER set-option -g status off || exit 1
+	$OUTER set-option -g window-size manual || exit 1
+	$OUTER set-option -g default-terminal screen || exit 1
+	$OUTER respawn-pane -k -t outer:0.0 \
+	    "$TEST_TMUX -Lredraw-write-inner-$$-$N -f/dev/null attach-session -t inner" ||
+	    exit 1
+}
+
+trigger()
+{
+	: >"$DIR/trigger-$N-${1:-1}"
+}
+
+cat >"$EMITTER" <<'PERL'
+use strict;
+use warnings;
+
+$| = 1;
+my $mode = $ENV{MODE};
+my $ready = $ENV{READY};
+my $trigger = $ENV{TRIGGER};
+
+sub fill_screen {
+	my ($prefix) = @_;
+	print "\e[2J\e[H";
+	for my $row (0 .. 11) {
+		printf "\e[%d;1H%s-ROW-%02d", $row + 1, $prefix, $row;
+	}
+}
+
+if ($mode eq 'ris') {
+	fill_screen('RIS');
+} elsif ($mode eq 'alternate') {
+	fill_screen('BASE');
+} elsif ($mode eq 'scroll') {
+	fill_screen('SCROLL');
+} else {
+	die "unknown mode $mode\n";
+}
+
+open my $fh, '>', $ready or die "$ready: $!\n";
+close $fh;
+while (!-e "$trigger-1") {
+	select undef, undef, undef, 0.01;
+}
+
+if ($mode eq 'ris') {
+	print "\ec";
+} elsif ($mode eq 'alternate') {
+	print "\e[?1049h";
+	fill_screen('ALT');
+	while (!-e "$trigger-2") {
+		select undef, undef, undef, 0.01;
+	}
+	print "\e[?1049l";
+} else {
+	print "\e[12;1H\r\nSCROLL-NEW";
+}
+sleep 100;
+PERL
+
+# RIS clears the complete screen. The source pane and attached client must both
+# lose every old row.
+setup ris
+wait_outer_has RIS-ROW-11
+trigger
+wait_inner_lacks RIS-ROW
+wait_outer_lacks RIS-ROW
+
+# Leaving the alternate screen restores every row of the base screen.
+setup alternate
+wait_outer_has BASE-ROW-11
+trigger
+wait_inner_has ALT-ROW-11
+wait_outer_has ALT-ROW-11
+wait_outer_lacks BASE-ROW
+trigger 2
+wait_inner_has BASE-ROW-11
+wait_outer_has BASE-ROW-11
+wait_outer_lacks ALT-ROW
+
+# Scrolling a pane which is narrower than the terminal redraws its complete
+# region. Check the physical client row by row after the source grid shifts.
+setup scroll
+$INNER split-window -h -t inner:0 'sleep 100' || exit 1
+wait_outer_has SCROLL-ROW-11
+trigger
+wait_inner_has SCROLL-NEW
+wait_outer_has SCROLL-NEW
+row=1
+while [ "$row" -le 11 ]; do
+	expected=$(printf 'SCROLL-ROW-%02d' "$row")
+	actual=$(sed -n "${row}p" "$CAPTURE")
+	case "$actual" in
+	"$expected"*) ;;
+	*) fail "outer row $row was not redrawn as $expected" ;;
+	esac
+	row=$((row + 1))
+done
+actual=$(sed -n '12p' "$CAPTURE")
+case "$actual" in
+SCROLL-NEW*) ;;
+*) fail "outer bottom row was not redrawn as SCROLL-NEW" ;;
+esac
+
+exit 0

regress/renumber-window-limit.sh

@@ -0,0 +1,49 @@
+#!/bin/sh
+
+# renumber-windows with more windows than fit above base-index
+
+PATH=/bin:/usr/bin
+TERM=screen
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+TMUX="$TEST_TMUX -LtestRWL$$"
+$TMUX kill-server 2>/dev/null
+
+TMP=$(mktemp)
+CONF=$(mktemp)
+trap "rm -f $TMP $CONF" 0 1 15
+
+cat <<EOF >$CONF
+set -g base-index 10
+set -g renumber-windows on
+EOF
+
+$TMUX -f$CONF new -d -s a
+$TMUX neww -d -t a
+$TMUX neww -d -t a
+echo $($TMUX lsw -t a -F'#{window_index}') >$TMP
+(echo "10 11 12"|cmp -s - $TMP) || exit 1
+$TMUX killw -t a:11
+echo $($TMUX lsw -t a -F'#{window_index}') >$TMP
+(echo "10 11"|cmp -s - $TMP) || exit 1
+$TMUX kill-server 2>/dev/null
+
+cat <<EOF >$CONF
+set -g base-index 2147483646
+set -g renumber-windows on
+EOF
+
+$TMUX -f$CONF new -d -s a
+$TMUX neww -d -t a
+$TMUX neww -d -t a
+$TMUX neww -d -t a
+echo $($TMUX lsw -t a -F'#{window_index}') >$TMP
+(echo "0 1 2147483646 2147483647"|cmp -s - $TMP) || exit 1
+
+# Three windows do not fit from 2147483646, so the indexes stay as they are.
+$TMUX killw -t a:2147483647
+echo $($TMUX lsw -t a -F'#{window_index}') >$TMP
+(echo "0 1 2147483646"|cmp -s - $TMP) || exit 1
+$TMUX kill-server 2>/dev/null
+
+exit 0

regress/respawn-pane-control-lag.sh

@@ -15,7 +15,7 @@ PATH=/bin:/usr/bin
 TERM=screen
 
 [ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
-TMUX="$TEST_TMUX -Ltest"
+TMUX="$TEST_TMUX -Ltest$$"
 $TMUX kill-server 2>/dev/null
 
 DIR=$(mktemp -d)

regress/run-shell-cwd.sh

@@ -22,14 +22,26 @@ check_directory()
 	fi
 }
 
-# Expand the current pane's directory in the same command queue as creation.
+# The start path is available immediately, before the child is scheduled.
+# Use it to test the format context in the same command queue as creation.
 $TMUX new-session -d -s test -c "$TMP/first" 'sleep 60' \; \
-	 run-shell -c '#{pane_current_path}' "pwd >'$TMP/out'" || exit 1
+	 run-shell -c '#{pane_start_path}' "pwd >'$TMP/out'" || exit 1
 check_directory "$TMP/first"
 
 # An explicit target must supply the format context, including with a delay.
 pane=$($TMUX new-window -d -P -F '#{pane_id}' -t test \
 	-c "$TMP/second dir" 'sleep 60') || exit 1
+# The current path depends on the operating system finding the child process.
+i=0
+while [ "$($TMUX display-message -p -t "$pane" '#{pane_current_path}')" != \
+    "$TMP/second dir" ]; do
+	if [ "$i" -ge 100 ]; then
+		echo "Timed out waiting for pane current directory"
+		exit 1
+	fi
+	sleep 0.05
+	i=$((i + 1))
+done
 $TMUX run-shell -t "$pane" -d 0.1 -c '#{pane_current_path}' \
 	"pwd >'$TMP/out'" || exit 1
 check_directory "$TMP/second dir"

regress/screen-redraw-menus.sh

@@ -106,9 +106,28 @@ compare menu-over-split
 
 # Menu with no border lines.
 setup 40 14
-menu -b none -x6 -y8
+$TMUX2 display-menu -T "This title must not reserve width" -C 1 \
+    -b none -x6 -y8 \
+    "Alpha item" a "" \
+    "Beta item" b "" \
+    "" "" "" \
+    "Gamma item" g "" || exit 1
+sleep 1
 compare menu-noborder
 
+# Menu border style follows the explicitly targeted window, not the current
+# window when a different pane is selected.
+setup 40 14
+$TMUX2 set menu-border-lines none || exit 1
+$TMUX2 neww || exit 1
+$TMUX2 display-menu -t%0 -T "Menu" -C 1 \
+    "Alpha item" a "" \
+    "Beta item" b "" \
+    "" "" "" \
+    "Gamma item" g "" || exit 1
+$TMUX2 selectw -t%0 || exit 1
+compare menu-target-window-noborder
+
 # Menu with double border lines.
 setup 40 14
 menu -b double -x6 -y8

regress/screen-redraw-popups.sh

@@ -1,101 +0,0 @@
-#!/bin/sh
-
-# Exercise drawing of popups (display-popup) over the window scene. A popup is an
-# overlay drawn on top of the redraw scene (the overlay_draw path in
-# screen-redraw.c), so this guards against regressions in how popups appear.
-#
-# A popup is modal and stays open until its command exits, so each scene fully
-# re-creates the servers and re-attaches; the popup is opened in the background
-# (display-popup blocks the client that runs it) and the outer pane is captured
-# while it is open.
-#
-# Run with GENERATE=1 to (re)create the golden files.
-
-PATH=/bin:/usr/bin
-TERM=screen
-LC_ALL=C.UTF-8
-export TERM LC_ALL
-
-[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
-TMUX=
-TMUX2=
-SETUP=0
-RESULTS=screen-redraw-results
-
-TMP=$(mktemp)
-
-cleanup() {
-	rm -f "$TMP"
-	[ -n "$TMUX" ] && $TMUX kill-server 2>/dev/null
-	[ -n "$TMUX2" ] && $TMUX2 kill-server 2>/dev/null
-}
-trap cleanup 0 1 15
-
-fail() {
-	echo "$*" >&2
-	exit 1
-}
-
-compare() {
-	sleep 1
-	$TMUX capturep -p >$TMP || exit 1
-	if [ -n "$GENERATE" ]; then
-		cp $TMP "$RESULTS/$1.result" || exit 1
-		echo "generated $1"
-	else
-		cmp -s $TMP "$RESULTS/$1.result" || \
-			fail "scene $1 differs from $RESULTS/$1.result"
-	fi
-}
-
-C="sh -c 'i=0; while [ \$i -lt 13 ]; do printf \"POP%02d abcdefghij\n\" \$i; i=\$((i + 1)); done; exec sleep 100'"
-
-# setup: fresh inner window attached inside a fresh outer pane, 40x14.
-setup() {
-	[ -n "$TMUX" ] && $TMUX kill-server 2>/dev/null
-	[ -n "$TMUX2" ] && $TMUX2 kill-server 2>/dev/null
-	SETUP=$((SETUP + 1))
-	TMUX="$TEST_TMUX -LtestA$$-$SETUP -f/dev/null"
-	TMUX2="$TEST_TMUX -LtestB$$-$SETUP -f/dev/null"
-	$TMUX2 new -d -x40 -y14 "$C" || exit 1
-	$TMUX2 set -g status off || exit 1
-	$TMUX2 set -g window-size manual || exit 1
-	$TMUX2 resizew -x40 -y14 || exit 1
-	$TMUX new -d -x40 -y14 || exit 1
-	$TMUX set -g status off || exit 1
-	$TMUX set -g window-size manual || exit 1
-	$TMUX set -g default-terminal "tmux-256color" || exit 1
-	$TMUX send -l "$TMUX2 attach" || exit 1
-	$TMUX send Enter || exit 1
-	sleep 1
-}
-
-# popup <args>: open a popup running a fixed command, in the background (it stays
-# open because the command sleeps; the servers are killed at the next setup).
-popup() {
-	$TMUX2 display-popup "$@" -E "sh -c 'printf POPUP; exec sleep 100'" &
-	sleep 1
-}
-
-# Basic popup over a single pane.
-setup
-popup -w20 -h6 -x6 -y3
-compare popup-basic
-
-# Popup over a split: drawn on top of the pane border.
-setup
-$TMUX2 splitw -h "$C" || exit 1
-popup -w24 -h8 -x8 -y3
-compare popup-over-split
-
-# Popup with no border lines (-B).
-setup
-popup -B -w20 -h6 -x6 -y3
-compare popup-noborder
-
-# Popup with double border lines.
-setup
-popup -b double -w20 -h6 -x6 -y3
-compare popup-double
-
-exit 0

regress/screen-redraw-results/menu-noborder.result

@@ -1,11 +1,11 @@
 MENU00 abcdefghij
 MENU01 abcdefghij
-MENU02  Menu            
-MENU03  Alpha item (a)  
-MENU04  Beta item  (b)  
-MENU05                  
-MENU06  Gamma item (g)  
-MENU07                  
+MENU02 abcdefghij
+MENU03 abcdefghij
+MENU04 Alpha item (a) 
+MENU05 Beta item  (b) 
+MENU06                
+MENU07 Gamma item (g) 
 MENU08 abcdefghij
 MENU09 abcdefghij
 MENU10 abcdefghij

regress/screen-redraw-results/menu-target-window-noborder.result

@@ -0,0 +1,13 @@
+MENU00 abcdefghij
+MENU01 abcdefghij
+MENU02 abcdefghij
+MENU03 abcdefghij
+MENU04 abcd Alpha item (a) 
+MENU05 abcd Beta item  (b) 
+MENU06 abcd                
+MENU07 abcd Gamma item (g) 
+MENU08 abcdefghij
+MENU09 abcdefghij
+MENU10 abcdefghij
+MENU11 abcdefghij
+MENU12 abcdefghij

regress/screen-redraw-results/popup-basic.result

@@ -1,14 +0,0 @@
-POP00 ┌──────────────────┐
-POP01 │POPUP             │
-POP02 │                  │
-POP03 │                  │
-POP04 │                  │
-POP05 └──────────────────┘
-POP06 abcdefghij
-POP07 abcdefghij
-POP08 abcdefghij
-POP09 abcdefghij
-POP10 abcdefghij
-POP11 abcdefghij
-POP12 abcdefghij
-

regress/screen-redraw-results/popup-double.result

@@ -1,14 +0,0 @@
-POP00 ╔══════════════════╗
-POP01 ║POPUP             ║
-POP02 ║                  ║
-POP03 ║                  ║
-POP04 ║                  ║
-POP05 ╚══════════════════╝
-POP06 abcdefghij
-POP07 abcdefghij
-POP08 abcdefghij
-POP09 abcdefghij
-POP10 abcdefghij
-POP11 abcdefghij
-POP12 abcdefghij
-

regress/screen-redraw-results/popup-noborder.result

@@ -1,14 +0,0 @@
-POP00 POPUP
-POP01
-POP02
-POP03
-POP04
-POP05
-POP06 abcdefghij
-POP07 abcdefghij
-POP08 abcdefghij
-POP09 abcdefghij
-POP10 abcdefghij
-POP11 abcdefghij
-POP12 abcdefghij
-

regress/screen-redraw-results/popup-over-split.result

@@ -1,14 +0,0 @@
-POP00 ab┌──────────────────────┐fghij
-POP01 ab│POPUP                 │fghij
-POP02 ab│                      │fghij
-POP03 ab│                      │fghij
-POP04 ab│                      │fghij
-POP05 ab│                      │fghij
-POP06 ab│                      │fghij
-POP07 ab└──────────────────────┘fghij
-POP08 abcdefghij    │POP08 abcdefghij
-POP09 abcdefghij    │POP09 abcdefghij
-POP10 abcdefghij    │POP10 abcdefghij
-POP11 abcdefghij    │POP11 abcdefghij
-POP12 abcdefghij    │POP12 abcdefghij
-                    │

regress/screen-redraw-tiled.sh

@@ -95,7 +95,8 @@ layout_tee_down() {		# top/bottom, bottom split: a top tee
 $TMUX kill-server 2>/dev/null
 $TMUX2 kill-server 2>/dev/null
 
-$TMUX2 new -d -x40 -y14 "sh -c 'exec sleep 100'" || exit 1
+# Keep the anchor window alive until cleanup, even on slow test runs.
+$TMUX2 new -d -x40 -y14 'exec cat' || exit 1
 $TMUX2 set -g status off || exit 1
 $TMUX2 set -g window-size manual || exit 1
 $TMUX2 set -g pane-border-format " #{pane_index} " || exit 1

regress/switch-client-redraw.sh

@@ -0,0 +1,81 @@
+#!/bin/sh
+
+# Switching windows in the same session must redraw the attached client. The
+# session object is shared, so its current winlink cannot be compared after it
+# has already been changed.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+INNER="$TEST_TMUX -Lswitch-redraw-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Lswitch-redraw-outer-$$ -f/dev/null"
+CAPTURE=$DIR/capture
+
+fail()
+{
+	echo "$*" >&2
+	[ -s "$CAPTURE" ] && cat "$CAPTURE" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+wait_for_client()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		CLIENT=$($INNER list-clients -F '#{client_name}' 2>/dev/null)
+		[ -n "$CLIENT" ] && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "inner client did not attach"
+}
+
+wait_outer_has()
+{
+	marker=$1
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t outer:0.0 >"$CAPTURE" 2>/dev/null || true
+		grep -q "$marker" "$CAPTURE" && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "outer client did not show $marker"
+}
+
+$INNER new-session -d -s inner -x 40 -y 8 \
+    "printf '\033[2J\033[HA-WINDOW'; exec sleep 100" || exit 1
+$INNER new-window -d -t inner:1 \
+    "printf '\033[2J\033[HB-WINDOW'; exec sleep 100" || exit 1
+$INNER set-option -g status off || exit 1
+$INNER set-option -g window-size manual || exit 1
+
+$OUTER new-session -d -s outer -x 40 -y 8 'sleep 100' || exit 1
+$OUTER set-option -g status off || exit 1
+$OUTER set-option -g window-size manual || exit 1
+$OUTER respawn-pane -k -t outer:0.0 \
+    "$TEST_TMUX -Lswitch-redraw-inner-$$ -f/dev/null attach-session -t inner:0" ||
+    exit 1
+
+wait_for_client
+wait_outer_has A-WINDOW
+
+$INNER switch-client -c "$CLIENT" -t inner:1.0 || exit 1
+[ "$($INNER display-message -p -t inner '#{window_index}')" -eq 1 ] ||
+    fail "server did not select window 1"
+wait_outer_has B-WINDOW
+
+exit 0

regress/sync-output-scroll-clients.sh

@@ -0,0 +1,123 @@
+#!/bin/sh
+
+# A scroll held back by a synchronized update may be sent to all clients while
+# a later client is being redrawn. An earlier client which cannot scroll the
+# pane itself must still end up with the right contents.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+TMUX_TMPDIR=$DIR
+export TMUX_TMPDIR
+
+INNER="$TEST_TMUX -Li$$ -f/dev/null"
+OUTER="$TEST_TMUX -Lo$$ -f/dev/null"
+CONTROL=$DIR/control
+EMITTER=$DIR/emitter.pl
+
+fail()
+{
+	echo "$*" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+wait_for_file()
+{
+	i=0
+	while [ "$i" -lt 50 ] && [ ! -e "$1" ]; do
+		sleep 0.1
+		i=$((i + 1))
+	done
+	[ -e "$1" ] || fail "$2"
+}
+
+wait_for_clients()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		n=$($INNER list-clients 2>/dev/null | wc -l)
+		[ "$n" -eq "$1" ] && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "client $1 did not attach"
+}
+
+cat >"$EMITTER" <<'PERL'
+use strict;
+use warnings;
+
+my $control = $ENV{CONTROL};
+(my $dir = $control) =~ s{/[^/]+$}{};
+
+my @rows;
+for my $row (1 .. 24) {
+	push @rows, sprintf("INIT_ROW_%02d_", $row) . ('X' x 16);
+}
+syswrite STDOUT, "\e[H" . join("\r\n", @rows);
+
+open my $painted, '>', "$dir/painted" or die "$dir/painted: $!\n";
+close $painted;
+while (!-e $control) {
+	select undef, undef, undef, 0.01;
+}
+
+# Start a synchronized update and scroll, but do not end it.
+syswrite STDOUT, "\e[?2026h\e[24;1H\r\nSCROLLED_LINE_";
+open my $scrolled, '>', "$dir/scrolled" or die "$dir/scrolled: $!\n";
+close $scrolled;
+select undef, undef, undef, 3;
+PERL
+
+$INNER new-session -d -s inner -x 80 -y 24 \
+    "CONTROL='$CONTROL' perl '$EMITTER'" || exit 1
+$INNER set-option -g status off || exit 1
+$INNER set-option -g window-size manual || exit 1
+$INNER set-option -as terminal-features '*:sync' || exit 1
+
+# The pane is not full width, so clients cannot scroll it.
+$INNER split-window -h -d -t inner:0.0 'sleep 30' || exit 1
+
+for name in a b; do
+	$OUTER new-session -d -s $name -x 80 -y 24 \
+	    "$TEST_TMUX -Li$$ -f/dev/null attach-session -t inner" || exit 1
+	$OUTER set-option -t $name status off || exit 1
+	if [ "$name" = a ]; then
+		wait_for_clients 1
+	fi
+done
+$OUTER set-option -g window-size manual || exit 1
+wait_for_clients 2
+B=$($OUTER display-message -p -t b: '#{pane_tty}') || exit 1
+
+wait_for_file "$DIR/painted" "application did not paint"
+sleep 1
+: >"$CONTROL"
+wait_for_file "$DIR/scrolled" "application did not scroll"
+sleep 0.2
+
+# Redraw only the second client while the update is still in progress.
+$INNER refresh-client -t "$B" || exit 1
+sleep 1
+
+$OUTER capture-pane -p -t a: >"$DIR/a" || exit 1
+$OUTER capture-pane -p -t b: >"$DIR/b" || exit 1
+sed -n 1p "$DIR/b" | grep -q '^INIT_ROW_02_' ||
+    fail "second client not scrolled"
+sed -n 24p "$DIR/b" | grep -q '^SCROLLED_LINE_' ||
+    fail "second client missing scrolled line"
+cmp -s "$DIR/a" "$DIR/b" || fail "first client differs from second client"
+exit 0

regress/sync-output-scroll.sh

@@ -0,0 +1,150 @@
+#!/bin/sh
+
+# Check that synchronized scrolling does not redraw unchanged lines.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+TMUX_TMPDIR=$DIR
+export TMUX_TMPDIR
+
+INNER="$TEST_TMUX -Li$$ -f/dev/null"
+OUTER="$TEST_TMUX -Lo$$ -f/dev/null"
+CLIENT_BYTES=$DIR/client-bytes
+CONTROL=$DIR/control
+EMITTER=$DIR/emitter.pl
+
+fail()
+{
+	echo "$*" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+wait_for_file()
+{
+	i=0
+	while [ "$i" -lt 50 ] && [ ! -e "$1" ]; do
+		sleep 0.1
+		i=$((i + 1))
+	done
+	[ -e "$1" ] || fail "$2"
+}
+
+wait_for_client()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$INNER list-clients -F '#{client_termfeatures}' 2>/dev/null |
+		    grep -q 'sync' && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "sync-capable client did not attach"
+}
+
+wait_for_stable_bytes()
+{
+	previous=-1
+	stable=0
+	i=0
+	while [ "$i" -lt 50 ]; do
+		current=$(wc -c <"$CLIENT_BYTES" 2>/dev/null) || current=0
+		if [ "$current" -gt 0 ] && [ "$current" -eq "$previous" ]; then
+			stable=$((stable + 1))
+			[ "$stable" -eq 5 ] && return 0
+		else
+			stable=0
+		fi
+		previous=$current
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "client byte stream did not become stable"
+}
+
+cat >"$EMITTER" <<'PERL'
+use strict;
+use warnings;
+
+my $control = $ENV{CONTROL};
+(my $dir = $control) =~ s{/[^/]+$}{};
+
+# Fill the screen outside a synchronized update.
+my @rows;
+for my $row (1 .. 24) {
+	push @rows, substr(sprintf("INIT_ROW_%02d_", $row) . ('X' x 79), 0, 79);
+}
+syswrite STDOUT, "\e[H" . join("\r\n", @rows);
+
+open my $painted, '>', "$dir/painted" or die "$dir/painted: $!\n";
+close $painted;
+while (!-e $control) {
+	select undef, undef, undef, 0.01;
+}
+
+# Scroll one line and overwrite text in a synchronized update.
+my $frame = "\e[?2026h" .
+    "\e[24;1H\r\nSCROLLED_LINE_" .
+    "\e[23;60HCHANGED_" .
+    "\e[?2026l";
+my $written = syswrite STDOUT, $frame;
+die "short synchronized frame write\n"
+    unless defined $written && $written == length $frame;
+select undef, undef, undef, 3;
+PERL
+
+$INNER new-session -d -s inner -x 80 -y 24 \
+    "CONTROL='$CONTROL' perl '$EMITTER'" || exit 1
+$INNER set-option -g status off || exit 1
+$INNER set-option -g window-size manual || exit 1
+$INNER set-option -as terminal-features '*:sync' || exit 1
+
+$OUTER new-session -d -s outer -x 80 -y 24 \
+    "$TEST_TMUX -Li$$ -f/dev/null attach-session -t inner" ||
+    exit 1
+$OUTER set-option -g status off || exit 1
+$OUTER set-option -g window-size manual || exit 1
+wait_for_client
+
+wait_for_file "$DIR/painted" "application did not paint"
+sleep 1
+$OUTER pipe-pane -O -t outer:0.0 "cat >'$CLIENT_BYTES'" || exit 1
+: >"$CONTROL"
+i=0
+while [ "$i" -lt 50 ]; do
+	grep -q 'SCROLLED_LINE_' "$CLIENT_BYTES" 2>/dev/null && break
+	sleep 0.1
+	i=$((i + 1))
+done
+grep -q 'SCROLLED_LINE_' "$CLIENT_BYTES" || fail "scrolled line not sent"
+wait_for_stable_bytes
+$OUTER pipe-pane -t outer:0.0 || exit 1
+
+# Check that only changed lines are redrawn.
+grep -q 'CHANGED_' "$CLIENT_BYTES" || fail "changed cell not sent"
+if grep -q 'INIT_ROW_05_' "$CLIENT_BYTES"; then
+	fail "unchanged line redrawn after synchronized scroll"
+fi
+
+# The client must show the scrolled screen.
+$OUTER capture-pane -p -t outer:0.0 >"$DIR/screen" || exit 1
+sed -n 1p "$DIR/screen" | grep -q '^INIT_ROW_02_' ||
+    fail "first line not scrolled"
+sed -n 23p "$DIR/screen" | grep -q 'INIT_ROW_24_.*CHANGED_' ||
+    fail "changed cell not on screen"
+sed -n 24p "$DIR/screen" | grep -q '^SCROLLED_LINE_' ||
+    fail "scrolled line not on screen"
+exit 0

regress/sync-output-wrapped.sh

@@ -0,0 +1,116 @@
+#!/bin/sh
+
+# When only some lines are redrawn after a synchronized update, a line
+# following a wrapped line must be drawn at its own position, not where the
+# cursor happens to be.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+TMUX_TMPDIR=$DIR
+export TMUX_TMPDIR
+
+INNER="$TEST_TMUX -Li$$ -f/dev/null"
+OUTER="$TEST_TMUX -Lo$$ -f/dev/null"
+CONTROL=$DIR/control
+EMITTER=$DIR/emitter.pl
+
+fail()
+{
+	echo "$*" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+wait_for_file()
+{
+	i=0
+	while [ "$i" -lt 50 ] && [ ! -e "$1" ]; do
+		sleep 0.1
+		i=$((i + 1))
+	done
+	[ -e "$1" ] || fail "$2"
+}
+
+wait_for_client()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$INNER list-clients -F '#{client_termfeatures}' 2>/dev/null |
+		    grep -q 'sync' && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "sync-capable client did not attach"
+}
+
+cat >"$EMITTER" <<'PERL'
+use strict;
+use warnings;
+
+my $control = $ENV{CONTROL};
+(my $dir = $control) =~ s{/[^/]+$}{};
+
+# Fill the screen with 80 column lines and no newlines so every line wraps.
+my $out = "\e[H\e[2J";
+for my $row (1 .. 24) {
+	$out .= substr(sprintf("ROW%02d_", $row) . ('x' x 80), 0, 80);
+}
+syswrite STDOUT, $out . "\e[1;1H";
+
+open my $painted, '>', "$dir/painted" or die "$dir/painted: $!\n";
+close $painted;
+while (!-e $control) {
+	select undef, undef, undef, 0.01;
+}
+
+# Change rows 2 and 6 in one synchronized update.
+my $frame = "\e[?2026h" .
+    "\e[2;1H" . substr("NEW02_" . ('#' x 80), 0, 80) .
+    "\e[6;1H" . substr("NEW06_" . ('%' x 80), 0, 80) .
+    "\e[24;1H" .
+    "\e[?2026l";
+my $written = syswrite STDOUT, $frame;
+die "short synchronized frame write\n"
+    unless defined $written && $written == length $frame;
+open my $done, '>', "$dir/done" or die "$dir/done: $!\n";
+close $done;
+select undef, undef, undef, 3;
+PERL
+
+$INNER new-session -d -s inner -x 80 -y 24 \
+    "CONTROL='$CONTROL' perl '$EMITTER'" || exit 1
+$INNER set-option -g status off || exit 1
+$INNER set-option -g window-size manual || exit 1
+$INNER set-option -as terminal-features '*:sync' || exit 1
+
+$OUTER new-session -d -s outer -x 80 -y 24 \
+    "$TEST_TMUX -Li$$ -f/dev/null attach-session -t inner" ||
+    exit 1
+$OUTER set-option -g status off || exit 1
+$OUTER set-option -g window-size manual || exit 1
+wait_for_client
+
+wait_for_file "$DIR/painted" "application did not paint"
+sleep 1
+: >"$CONTROL"
+wait_for_file "$DIR/done" "application did not finish"
+sleep 1
+
+$OUTER capture-pane -p -t outer:0.0 >"$DIR/screen" || exit 1
+sed -n 2p "$DIR/screen" | grep -q '^NEW02_#' || fail "row 2 not redrawn"
+sed -n 3p "$DIR/screen" | grep -q '^ROW03_x' || fail "row 3 overwritten"
+sed -n 6p "$DIR/screen" | grep -q '^NEW06_%' || fail "row 6 not redrawn"
+exit 0

regress/tty-keys.sh

@@ -9,14 +9,37 @@ $TMUX kill-server 2>/dev/null
 TMUX2="$TEST_TMUX -LtestB$$ -f/dev/null"
 $TMUX2 kill-server 2>/dev/null
 
-TMP=$(mktemp)
-trap "rm -f $TMP" 0 1 15
+TMP=$(mktemp) || exit 1
+prompt_pid=
+
+cleanup () {
+	if [ -n "$prompt_pid" ]; then
+		kill "$prompt_pid" 2>/dev/null
+		wait "$prompt_pid" 2>/dev/null
+	fi
+	$TMUX kill-server 2>/dev/null
+	$TMUX2 kill-server 2>/dev/null
+	rm -f "$TMP"
+}
+trap cleanup 0
+trap 'exit 1' 1 2 15
+
+fail () {
+	echo "[FAIL] $*" >&2
+	exit 1
+}
 
 $TMUX2 -f/dev/null new -d || exit 1
 $TMUX -f/dev/null new -d "$TMUX2 attach" || exit 1
-sleep 1
+i=0
+while [ -z "$($TMUX2 list-clients -F '#{client_name}')" ]; do
+	[ "$i" -lt 100 ] || fail "inner client did not attach"
+	sleep 0.05
+	i=$((i + 1))
+done
 
 exit_status=0
+assertion=0
 
 format_string () {
 	case $1 in
@@ -34,12 +57,33 @@ assert_key () {
 	expected_name=$2
 	format_string=$(format_string "$expected_name")
 
-	$TMUX2 command-prompt -k 'display-message -pl '"$format_string" > "$TMP" &
-	sleep 0.05
+	# Use a different prompt each time so a stale redraw cannot look ready.
+	assertion=$((assertion + 1))
+	prompt="tty-keys-$assertion:"
+	$TMUX2 command-prompt -k -p "$prompt" \
+	    'display-message -pl '"$format_string" > "$TMP" &
+	prompt_pid=$!
+	i=0
+	while ! $TMUX capture-pane -p | grep -Fq "$prompt"; do
+		kill -0 "$prompt_pid" 2>/dev/null || \
+		    fail "$keys -> $expected_name: prompt exited before becoming ready"
+		[ "$i" -lt 100 ] || \
+		    fail "$keys -> $expected_name: timed out waiting for prompt"
+		sleep 0.05
+		i=$((i + 1))
+	done
 
-	$TMUX send-keys $keys
+	$TMUX send-keys $keys || fail "could not send $keys"
 
-	wait
+	i=0
+	while kill -0 "$prompt_pid" 2>/dev/null; do
+		[ "$i" -lt 100 ] || \
+		    fail "$keys -> $expected_name: timed out waiting for key"
+		sleep 0.05
+		i=$((i + 1))
+	done
+	wait "$prompt_pid" || fail "$keys -> $expected_name: prompt failed"
+	prompt_pid=
 
 	keys=$(printf '%s' "$keys" | sed -e 's/Escape/\\\\033/g' | tr -d '[:space:]')
 	actual_name=$(tr -d '[:space:]' < "$TMP")
@@ -365,7 +409,4 @@ assert_key 'Escape [32;2u' 'S-Space'
 assert_key 'Escape [9;5u' 'C-Tab'
 assert_key 'Escape [1;5Z' 'C-S-Tab'
 
-$TMUX kill-server 2>/dev/null
-$TMUX2 kill-server 2>/dev/null
-
 exit $exit_status

regress/tty-margins-scrollbar.sh

@@ -0,0 +1,93 @@
+#!/bin/sh
+
+# With left/right margins, a pane narrowed by a scrollbar can scroll without
+# retransmitting its existing rows. Both paths must produce the same screen.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+INNER="$TEST_TMUX -Lmarginsscrollbar-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Lmarginsscrollbar-outer-$$ -f/dev/null"
+
+fail()
+{
+	echo "$*" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+cat >"$DIR/emitter.pl" <<'PERL'
+use strict;
+use warnings;
+$| = 1;
+print join("\r\n", map { "KEEP0$_" } 1 .. 6);
+while (!-e $ENV{TRIGGER}) {
+	select undef, undef, undef, 0.01;
+}
+print "\r\nNEWROW";
+sleep 100;
+PERL
+
+for margins in on off; do
+	$INNER new-session -d -s inner -x 40 -y 6 \
+	    "TRIGGER='$DIR/trigger-$margins' perl '$DIR/emitter.pl'" || exit 1
+	$INNER set -g status off || exit 1
+	$INNER set -g status-interval 0 || exit 1
+	$INNER set -g automatic-rename off || exit 1
+	$INNER set -g window-size manual || exit 1
+	$INNER set -g pane-scrollbars on || exit 1
+	if [ "$margins" = on ]; then
+		$INNER set -as terminal-features ',screen-256color:margins' || exit 1
+	fi
+
+	$OUTER new-session -d -s outer -x 40 -y 6 'sleep 100' || exit 1
+	$OUTER set -g status off || exit 1
+	$OUTER set -g window-size manual || exit 1
+	$OUTER set -g default-terminal screen-256color || exit 1
+	$OUTER respawn-pane -k -t outer:0.0 "$INNER attach -t inner" || exit 1
+	sleep 0.5
+	$OUTER pipe-pane -O -t outer:0.0 "cat >'$DIR/output-$margins'" || exit 1
+	$INNER refresh-client || exit 1
+	sleep 0.5
+	grep -aq KEEP02 "$DIR/output-$margins" || fail "initial rows not captured"
+	offset=$(wc -c <"$DIR/output-$margins")
+	: >"$DIR/trigger-$margins"
+	i=0
+	while [ "$i" -lt 50 ]; do
+		$OUTER capture-pane -p -t outer:0.0 >"$DIR/screen-$margins" || exit 1
+		grep -q NEWROW "$DIR/screen-$margins" && break
+		sleep 0.1
+		i=$((i + 1))
+	done
+	[ "$i" -lt 50 ] || fail "$margins: scroll did not reach the terminal"
+	sleep 0.2
+	tail -c +"$((offset + 1))" "$DIR/output-$margins" >"$DIR/scroll-$margins"
+	grep -aq NEWROW "$DIR/scroll-$margins" || fail "scroll output not captured"
+	if [ "$margins" = on ]; then
+		if grep -aq KEEP02 "$DIR/scroll-$margins"; then
+			fail "scroll with margins retransmitted an existing row"
+		fi
+	else
+		grep -aq KEEP02 "$DIR/scroll-$margins" ||
+		    fail "scroll without margins did not exercise the redraw fallback"
+	fi
+	printf 'KEEP02\nKEEP03\nKEEP04\nKEEP05\nKEEP06\nNEWROW\n' >"$DIR/expected"
+	cmp -s "$DIR/expected" "$DIR/screen-$margins" ||
+	    fail "$margins: terminal did not contain the expected scrolled rows"
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+done
+
+exit 0

regress/wait-for-client-lost.sh

@@ -0,0 +1,164 @@
+#!/bin/sh
+
+# A disconnected waiter must release both its wait and its command queue.
+PATH=/bin:/usr/bin
+TERM=screen
+export TERM
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+OUT=$(mktemp -d)
+TMUX="$TEST_TMUX -S$OUT/socket -f/dev/null"
+pids=
+
+cleanup()
+{
+	for pid in $pids; do
+		kill "$pid" 2>/dev/null || true
+	done
+	$TMUX kill-server 2>/dev/null || true
+	rm -rf "$OUT"
+}
+trap cleanup EXIT
+
+fail()
+{
+	echo "$*" >&2
+	exit 1
+}
+
+wait_list()
+{
+	expected=$1
+	shift
+	i=0
+	while [ $i -lt 100 ]; do
+		value=$($TMUX wait-for -l "$@") || fail "list waiters failed"
+		[ "$value" = "$expected" ] && return
+		i=$((i + 1))
+		sleep 0.05
+	done
+	fail "expected waiters '$expected', got '$value'"
+}
+
+wait_free()
+{
+	client_pid=$1
+	i=0
+	while [ $i -lt 100 ]; do
+		awk -v pid="$client_pid" '
+		    $4 == "IDENTIFY_CLIENTPID" && $5 == pid { address = $3 }
+		    address != "" && $2 == "free" && $3 == "client" &&
+		    $4 == address && $5 == "(0" { freed = 1 }
+		    END { exit !freed }
+		' "$OUT"/tmux-server-*.log && return
+		i=$((i + 1))
+		sleep 0.05
+	done
+	fail "client $client_pid was not freed"
+}
+
+cd "$OUT" || exit 1
+$TMUX -vv new-session -d -s test || fail "new-session failed"
+$TMUX set -g @continued 0 || fail "set option failed"
+
+for signal in TERM KILL; do
+	for kind in channel lock event; do
+		name="$kind-$signal"
+		case $kind in
+		channel) args="$name"; list_args="$name" ;;
+		lock)
+			$TMUX wait-for -L "$name" || fail "lock failed"
+			args="-L $name"; list_args="$name"
+			;;
+		event) args="-E @$name"; list_args="-E @$name" ;;
+		esac
+
+		$TMUX wait-for $args \; set -g @continued 1 &
+		dead=$!
+		pids="$dead"
+		wait_list "client-$dead" $list_args
+
+		$TMUX wait-for $args &
+		live=$!
+		pids="$dead $live"
+		wait_list "$(printf 'client-%s\nclient-%s' "$dead" "$live")" \
+		    $list_args
+
+		kill -"$signal" "$dead" || fail "kill failed"
+		wait "$dead" 2>/dev/null || true
+		pids="$live"
+		wait_list "client-$live" $list_args
+		wait_free "$dead"
+		[ "$($TMUX show -gqv @continued)" = 0 ] ||
+			fail "disconnected client's next command ran"
+
+		case $kind in
+		channel) $TMUX wait-for -S "$name" || fail "signal failed" ;;
+		lock) $TMUX wait-for -U "$name" || fail "unlock failed" ;;
+		event)
+			$TMUX wait-for -E -w "client-$live" "@$name" ||
+				fail "wake event waiter failed"
+			;;
+		esac
+		wait_list "" $list_args
+		wait_free "$live"
+		wait "$live" || fail "surviving waiter failed"
+		pids=
+		if [ "$kind" = lock ]; then
+			$TMUX wait-for -U "$name" || fail "final unlock failed"
+		fi
+	done
+done
+
+# Removing the last waiter must remove its otherwise unused channel, and must
+# not create a pending signal. Unrelated pending signals must be preserved.
+$TMUX wait-for -S saved || fail "save signal failed"
+$TMUX wait-for last &
+dead=$!
+pids="$dead"
+wait_list "client-$dead" last
+kill -KILL "$dead" || fail "kill last waiter failed"
+wait "$dead" 2>/dev/null || true
+pids=
+wait_list "" last
+wait_free "$dead"
+grep -F 'remove empty wait channel last' "$OUT"/tmux-server-*.log \
+    >/dev/null || fail "empty channel was not removed"
+
+$TMUX wait-for saved \; wait-for last &
+live=$!
+pids="$live"
+wait_list "client-$live" last
+$TMUX wait-for -S last || fail "signal last failed"
+wait_free "$live"
+wait "$live" || fail "pending signal was not preserved"
+pids=
+
+# Source-file leaves a cleanup callback behind the blocked command.
+printf 'wait-for sourced\nset -g @continued 1\n' >"$OUT/source.conf"
+$TMUX source-file "$OUT/source.conf" &
+dead=$!
+pids="$dead"
+wait_list "client-$dead" sourced
+kill -KILL "$dead" || fail "kill source-file waiter failed"
+wait "$dead" 2>/dev/null || true
+pids=
+wait_list "" sourced
+wait_free "$dead"
+[ "$($TMUX show -gqv @continued)" = 0 ] ||
+	fail "disconnected source-file client's next command ran"
+
+# Firing an event after cancellation must not call the removed event sink.
+$TMUX wait-for -E window-renamed &
+dead=$!
+pids="$dead"
+wait_list "client-$dead" -E window-renamed
+kill -KILL "$dead" || fail "kill event waiter failed"
+wait "$dead" 2>/dev/null || true
+pids=
+wait_list "" -E window-renamed
+wait_free "$dead"
+$TMUX rename-window -t test:0 renamed || fail "rename-window failed"
+$TMUX display-message -p '#{pid}' >/dev/null || fail "server exited"
+
+exit 0

regress/window-copy-scrollbar-drag-focus-style.sh

@@ -0,0 +1,123 @@
+#!/bin/sh
+
+# Dragging an inactive pane's scrollbar slider changes which pane is
+# active (window_copy_scroll(), window-copy.c). Every other place in the
+# codebase that changes the active pane pairs it with
+# window_redraw_active_switch() (or falls back to a full window redraw) so
+# the old/new active panes' window-active-style/window-style colours get
+# repainted - window_copy_scroll() was the one caller that did neither, so
+# a scrollbar-slider drag changed focus but left both panes' body colours
+# stale. This used to be masked by window_set_active_pane() itself doing
+# an unconditional full redraw on every active-pane change, until that was
+# narrowed to borders/status-only for the common case.
+#
+# This creates two tiled panes with clearly distinguishable
+# window-active-style/window-style backgrounds, puts the *inactive* one in
+# copy mode, drags its scrollbar slider, and checks - via an attached
+# client's own received bytes, since window-style is applied during
+# redraw composition rather than stored in the grid, so capture-pane
+# alone would not reflect it - that the newly active pane's marker text
+# immediately shows the active-style colour, not the stale one.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export PATH TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+
+DIR=$(mktemp -d) || exit 1
+INNER="$TEST_TMUX -Lsbfocus-inner-$$ -f/dev/null"
+OUTER="$TEST_TMUX -Lsbfocus-outer-$$ -f/dev/null"
+CAPTURE=$DIR/capture
+ESC=$(printf '\033')
+
+fail()
+{
+	echo "$*" >&2
+	[ -s "$CAPTURE" ] && cat -A "$CAPTURE" >&2
+	exit 1
+}
+
+cleanup()
+{
+	$OUTER kill-server 2>/dev/null
+	$INNER kill-server 2>/dev/null
+	rm -rf "$DIR"
+}
+trap cleanup 0 1 15
+
+get_mark_color()
+{
+	$OUTER capture-pane -e -p -t outer:0.0 >"$CAPTURE" 2>/dev/null || true
+	LC_ALL=C grep -a "MARK1" "$CAPTURE" |
+	    LC_ALL=C grep -aoE "${ESC}\[4[12]m" | tail -1
+}
+
+wait_mark_color()
+{
+	want=$1
+	i=0
+	while [ "$i" -lt 50 ]; do
+		[ "$(get_mark_color)" = "$want" ] && return 0
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "MARK1's pane never showed the expected background (wanted '$want', got '$(get_mark_color)')"
+}
+
+mouse()
+{
+	sequence=$(printf '\033[<%s;%s;%s%s' "$1" "$2" "$3" "$4")
+	$OUTER send-keys -t outer:0.0 -l "$sequence" || exit 1
+	sleep 0.1
+}
+
+$INNER new-session -d -s inner -x 40 -y 10 'sleep 100' || exit 1
+$INNER set-option -g status off || exit 1
+$INNER set-option -g window-size manual || exit 1
+$INNER set-option -g mouse on || exit 1
+$INNER set-option -g pane-scrollbars on || exit 1
+$INNER setw pane-scrollbars-position right || exit 1
+$INNER setw pane-scrollbars-style 'width=1,pad=0' || exit 1
+$INNER set-option -g window-active-style 'bg=red' || exit 1
+$INNER set-option -g window-style 'bg=green' || exit 1
+$INNER split-window -h -t inner -d 'printf MARK1; sleep 100' || exit 1
+
+PANE1=$($INNER list-panes -t inner -F '#{pane_id}' | sed -n 2p)
+[ "$($INNER display-message -p -t "$PANE1" '#{pane_active}')" = 0 ] ||
+	fail "sanity: MARK1's pane is already active before the drag"
+
+# Put the inactive pane in copy mode without switching focus (copy-mode -t
+# targets a pane without making it active).
+$INNER copy-mode -t "$PANE1" || exit 1
+
+$OUTER new-session -d -s outer -x 40 -y 10 'sleep 100' || exit 1
+$OUTER set-option -g status off || exit 1
+$OUTER set-option -g window-size manual || exit 1
+$OUTER set-option -g default-terminal screen-256color || exit 1
+$OUTER respawn-pane -k -t outer:0.0 \
+    "$TEST_TMUX -Lsbfocus-inner-$$ -f/dev/null attach-session -t inner" ||
+    exit 1
+
+wait_mark_color "${ESC}[42m"
+
+XOFF=$($INNER display-message -p -t "$PANE1" '#{pane_left}')
+YOFF=$($INNER display-message -p -t "$PANE1" '#{pane_top}')
+SX=$($INNER display-message -p -t "$PANE1" '#{pane_width}')
+SBCOL=$((XOFF + SX + 1))
+SBROW=$((YOFF + 1))
+
+# With no scrollback beyond the pane's own content, the slider fills the
+# whole scrollbar track, so any point on it (here, its very first row) is
+# on the slider.
+mouse 0 "$SBCOL" "$SBROW" M
+mouse 32 "$SBCOL" "$((SBROW + 1))" M
+mouse 0 "$SBCOL" "$((SBROW + 1))" m
+
+[ "$($INNER display-message -p -t "$PANE1" '#{pane_active}')" = 1 ] ||
+	fail "sanity: dragging the scrollbar slider did not change focus"
+
+wait_mark_color "${ESC}[41m"
+
+exit 0

regress/window-index-limit.sh

@@ -0,0 +1,26 @@
+#!/bin/sh
+
+# inserting a window next to the highest index
+
+PATH=/bin:/usr/bin
+TERM=screen
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+TMUX="$TEST_TMUX -LtestWIL$$ -f/dev/null"
+$TMUX kill-server 2>/dev/null
+
+TMP=$(mktemp)
+trap "rm -f $TMP" 0 1 15
+
+$TMUX new -d -s one
+$TMUX set -g base-index 2147483647
+$TMUX neww -d -t one
+
+$TMUX neww -d -a -t one:2147483647
+$TMUX neww -d -b -t one:2147483647
+
+echo $($TMUX lsw -t one -F'#{window_index}') >$TMP
+(echo "0 2147483647"|cmp -s - $TMP) || exit 1
+$TMUX kill-server 2>/dev/null
+
+exit 0

screen-redraw.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: screen-redraw.c,v 1.160 2026/09/21 10:22:31 nicm Exp $ */
+/* $OpenBSD: screen-redraw.c,v 1.162 2026/09/24 11:19:39 nicm Exp $ */
 
 /*
  * Copyright (c) 2026 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -204,14 +204,36 @@ struct redraw_scene {
 	u_int			 oy;
 };
 
+/* A damaged rectangle in a window. */
+struct redraw_damage {
+	u_int				 x;
+	u_int				 y;
+	u_int				 sx;
+	u_int				 sy;
+
+	TAILQ_ENTRY(redraw_damage)	entry;
+};
+
+/*
+ * If there are more damage rectangles than this, they are collapsed into
+ * one.
+ */
+#define REDRAW_DAMAGE_MAX 16
+
 /* Cell for building the scene. */
 struct redraw_build_cell {
 	struct redraw_span_data	 data;
 };
-
 static struct redraw_build_cell	*redraw_cells;
 static size_t			 redraw_ncells;
 
+/*
+ * We can reuse the same pane status lines during one damage redraw, but when
+ * we enter a new one, the client or format variables may have changed, so we
+ * need to make them again. The generation is increased so this happens.
+ */
+static u_int	redraw_status_generation;
+
 /* Context for building the scene. */
 struct redraw_build_ctx {
 	struct client				*c;
@@ -1054,6 +1076,13 @@ redraw_free_scene(struct redraw_scene *scene)
 	free(scene);
 }
 
+/* Does a client's cached scene show this window? */
+int
+redraw_client_has_window(struct client *c, struct window *w)
+{
+	return (c->redraw_scene != NULL && c->redraw_scene->w == w);
+}
+
 /* Mark a window's cached redraw scenes as out of date. */
 void
 redraw_invalidate_scene(struct window *w)
@@ -1061,6 +1090,104 @@ redraw_invalidate_scene(struct window *w)
 	w->redraw_scene_generation++;
 }
 
+/* Free all pending damage for a window. */
+void
+redraw_free_damage(struct window *w)
+{
+	struct redraw_damage	*rd, *rd1;
+
+	TAILQ_FOREACH_SAFE(rd, &w->damage, entry, rd1) {
+		TAILQ_REMOVE(&w->damage, rd, entry);
+		free(rd);
+	}
+	w->damage_count = 0;
+}
+
+/* Collapse all pending damage for a window into one rectangle. */
+static void
+redraw_collapse_damage(struct window *w)
+{
+	struct redraw_damage	*rd, *rd1, *first;
+	u_int			 x0, y0, x1, y1;
+
+	first = TAILQ_FIRST(&w->damage);
+	if (first == NULL)
+		return;
+	x0 = first->x;
+	y0 = first->y;
+	x1 = first->x + first->sx;
+	y1 = first->y + first->sy;
+
+	TAILQ_FOREACH_SAFE(rd, &w->damage, entry, rd1) {
+		if (rd->x < x0)
+			x0 = rd->x;
+		if (rd->y < y0)
+			y0 = rd->y;
+		if (rd->x + rd->sx > x1)
+			x1 = rd->x + rd->sx;
+		if (rd->y + rd->sy > y1)
+			y1 = rd->y + rd->sy;
+		if (rd != first) {
+			TAILQ_REMOVE(&w->damage, rd, entry);
+			free(rd);
+		}
+	}
+
+	first->x = x0;
+	first->y = y0;
+	first->sx = x1 - x0;
+	first->sy = y1 - y0;
+	w->damage_count = 1;
+}
+
+/* Record window damage, merging nearby rectangles and limiting the count. */
+void
+redraw_damage_window(struct window *w, u_int x, u_int y, u_int sx, u_int sy)
+{
+	struct redraw_damage	*rd;
+	u_int			 x0, y0, x1, y1, area, union_area;
+
+	if (x >= w->sx || y >= w->sy)
+		return;
+	if (x + sx > w->sx)
+		sx = w->sx - x;
+	if (y + sy > w->sy)
+		sy = w->sy - y;
+	if (sx == 0 || sy == 0)
+		return;
+
+	TAILQ_FOREACH(rd, &w->damage, entry) {
+		if (x > rd->x + rd->sx || rd->x > x + sx ||
+		    y > rd->y + rd->sy || rd->y > y + sy)
+			continue;
+
+		x0 = (x < rd->x) ? x : rd->x;
+		y0 = (y < rd->y) ? y : rd->y;
+		x1 = (x + sx > rd->x + rd->sx) ? x + sx : rd->x + rd->sx;
+		y1 = (y + sy > rd->y + rd->sy) ? y + sy : rd->y + rd->sy;
+
+		area = sx * sy + rd->sx * rd->sy;
+		union_area = (x1 - x0) * (y1 - y0);
+		if (union_area > 2 * area)
+			continue;
+
+		rd->x = x0;
+		rd->y = y0;
+		rd->sx = x1 - x0;
+		rd->sy = y1 - y0;
+		return;
+	}
+
+	rd = xcalloc(1, sizeof *rd);
+	rd->x = x;
+	rd->y = y;
+	rd->sx = sx;
+	rd->sy = sy;
+	TAILQ_INSERT_TAIL(&w->damage, rd, entry);
+	if (++w->damage_count > REDRAW_DAMAGE_MAX)
+		redraw_collapse_damage(w);
+}
+
 /* Mark all cached redraw scenes as out of date. */
 void
 redraw_invalidate_all_scenes(void)
@@ -1603,6 +1730,24 @@ redraw_set_draw_context(struct redraw_draw_ctx *dctx,
 		dctx->flags |= REDRAW_ISOLATES;
 }
 
+/* Build a pane prompt. */
+static void
+redraw_make_pane_prompt(struct window_pane *wp, struct screen *screen)
+{
+	struct screen_write_ctx	 ctx;
+	struct prompt_draw_data	 pdd;
+
+	screen_init(screen, wp->sx, 1, 0);
+	screen_write_start(&ctx, screen);
+	pdd.ctx = &ctx;
+	pdd.cursor_x = &wp->prompt_cx;
+	pdd.area_x = 0;
+	pdd.area_width = wp->sx;
+	pdd.prompt_line = 0;
+	prompt_draw(wp->prompt, &pdd);
+	screen_write_stop(&ctx);
+}
+
 /* Draw a pane's prompt over its content. */
 static void
 redraw_draw_pane_prompt(struct redraw_draw_ctx *dctx, struct window_pane *wp)
@@ -1611,8 +1756,6 @@ redraw_draw_pane_prompt(struct redraw_draw_ctx *dctx, struct window_pane *wp)
 	struct client		*c = scene->c;
 	struct tty		*tty = &c->tty;
 	struct screen		 screen;
-	struct screen_write_ctx	 ctx;
-	struct prompt_draw_data	 pdd;
 	int			 ox = scene->ox, oy = scene->oy;
 	int			 sx = scene->sx, sy = scene->sy;
 	int			 line, cy, px, offset, width, wy;
@@ -1645,17 +1788,8 @@ redraw_draw_pane_prompt(struct redraw_draw_ctx *dctx, struct window_pane *wp)
 	if (px + width > sx)
 		width = sx - px;
 
-	screen_init(&screen, wp->sx, 1, 0);
-	screen_write_start(&ctx, &screen);
-	pdd.ctx = &ctx;
-	pdd.cursor_x = &wp->prompt_cx;
-	pdd.area_x = 0;
-	pdd.area_width = wp->sx;
-	pdd.prompt_line = 0;
-	prompt_draw(wp->prompt, &pdd);
-	screen_write_stop(&ctx);
-
-	tty_draw_line(tty, &screen, 0, offset, width, px, cy, NULL);
+	redraw_make_pane_prompt(wp, &screen);
+	tty_draw_line(tty, &screen, offset, 0, width, px, cy, NULL);
 	screen_free(&screen);
 }
 
@@ -1684,7 +1818,9 @@ redraw_draw(struct client *c, struct window_pane *wp, int flags)
 			redraw = status_prompt_redraw(c);
 		else
 			redraw = status_redraw(c);
-		if (!redraw && !REDRAW_IS_ALL(flags)) {
+		if (!redraw &&
+		    (~c->flags & CLIENT_REDRAWSTATUSALWAYS) &&
+		    !REDRAW_IS_ALL(flags)) {
 			flags &= ~REDRAW_STATUS;
 			if (flags == 0)
 				return;
@@ -1738,14 +1874,14 @@ redraw_draw(struct client *c, struct window_pane *wp, int flags)
 		if (wp != NULL) {
 			if (wp->base.mode & MODE_SYNC)
 				screen_write_stop_sync(wp);
-			screen_write_clear_dirty(wp);
+			screen_write_sync_clear_dirty(wp);
 		} else {
 			TAILQ_FOREACH(loop, &scene->w->panes, entry) {
 				if (!window_pane_is_visible(loop))
 					continue;
 				if (loop->base.mode & MODE_SYNC)
 					screen_write_stop_sync(loop);
-				screen_write_clear_dirty(loop);
+				screen_write_sync_clear_dirty(loop);
 			}
 		}
 	}
@@ -1842,7 +1978,7 @@ redraw_screen(struct client *c)
 	else {
 		if (c->flags & CLIENT_REDRAWBORDERS)
 			flags |= (REDRAW_PANE_BORDER|REDRAW_PANE_STATUS);
-		if (c->flags & CLIENT_REDRAWSTATUS)
+		if (c->flags & (CLIENT_REDRAWSTATUS|CLIENT_REDRAWSTATUSALWAYS))
 			flags |= (REDRAW_STATUS|REDRAW_PANE_STATUS);
 		if (c->flags & CLIENT_REDRAWMENU)
 			flags |= REDRAW_MENU;
@@ -1868,3 +2004,138 @@ redraw_pane_scrollbar(struct client *c, struct window_pane *wp)
 {
 	redraw_draw(c, wp, REDRAW_PANE_SCROLLBAR);
 }
+
+/* Rebuild damaged pane status. */
+static void
+redraw_damage_refresh_status(struct redraw_draw_ctx *dctx,
+    struct window_pane *wp)
+{
+	struct redraw_span	*first;
+	u_int			 g = wp->status_generation, width;
+
+	if ((wp->flags & PANE_NEWSTATUS) && g == redraw_status_generation)
+		return;
+	width = redraw_pane_status_width(dctx, wp, &first);
+	if (width != 0) {
+		window_make_pane_status(wp, dctx->scene->c, width, first);
+		wp->flags |= PANE_NEWSTATUS;
+		wp->status_generation = redraw_status_generation;
+	}
+}
+
+/* Draw a pane's prompt over a damaged span. */
+static void
+redraw_damage_draw_pane_prompt(struct redraw_draw_ctx *dctx,
+    struct redraw_span *span, u_int y)
+{
+	struct redraw_scene	*scene = dctx->scene;
+	struct window_pane	*wp = span->data.p.wp;
+	struct tty		*tty = &scene->c->tty;
+	struct screen		 screen;
+	u_int			 px = span->data.p.px, width, prompt_y;
+
+	if (wp->prompt == NULL || wp->sx == 0 || wp->sy == 0)
+		return;
+	if (dctx->flags & REDRAW_STATUS_TOP)
+		prompt_y = 0;
+	else
+		prompt_y = wp->sy - 1;
+	if (span->data.p.py != prompt_y)
+		return;
+	redraw_make_pane_prompt(wp, &screen);
+	if (px < screen_size_x(&screen)) {
+		width = span->width;
+		if (width > screen_size_x(&screen) - px)
+			width = screen_size_x(&screen) - px;
+		tty_draw_line(tty, &screen, px, 0, width, span->x, y, NULL);
+	}
+	screen_free(&screen);
+}
+
+/* Draw the spans intersecting a damaged rectangle. */
+static void
+redraw_draw_damage_rectangle(struct redraw_draw_ctx *dctx, u_int x, u_int y,
+    u_int sx, u_int sy)
+{
+	struct redraw_scene	*scene = dctx->scene;
+	struct redraw_line	*line;
+	struct redraw_spans	*spans;
+	struct redraw_span	*span;
+	u_int			 cy, yy, type;
+
+	if (x >= scene->sx || y >= scene->sy)
+		return;
+	if (x + sx > scene->sx)
+		sx = scene->sx - x;
+	if (y + sy > scene->sy)
+		sy = scene->sy - y;
+	if (sx == 0 || sy == 0)
+		return;
+
+	for (yy = y; yy < y + sy; yy++) {
+		line = &scene->lines[yy];
+		if (dctx->flags & REDRAW_STATUS_TOP)
+			cy = dctx->status_lines + yy;
+		else
+			cy = yy;
+		for (type = 0; type < REDRAW_SPAN_TYPES; type++) {
+			spans = &line->spans[type];
+			TAILQ_FOREACH(span, spans, entry) {
+				if (span->x >= x + sx)
+					continue;
+				if (span->x + span->width <= x)
+					continue;
+				if (type == REDRAW_SPAN_STATUS) {
+					redraw_damage_refresh_status(dctx,
+					    span->data.st.wp);
+				}
+				redraw_draw_span(dctx, span, cy);
+				if (type == REDRAW_SPAN_PANE) {
+					redraw_damage_draw_pane_prompt(dctx,
+					    span, cy);
+				}
+			}
+		}
+	}
+}
+
+/* Draw pending window damage on this client. */
+void
+redraw_client_damage(struct client *c)
+{
+	struct window		*w = c->session->curw->window;
+	struct window_pane	*wp;
+	struct redraw_scene	*scene;
+	struct redraw_draw_ctx	 dctx;
+	struct redraw_damage	*rd;
+	u_int			 ox, oy, sx, sy, x0, y0, x1, y1;
+
+	if (TAILQ_EMPTY(&w->damage))
+		return;
+	redraw_status_generation++;
+
+	scene = redraw_get_scene(c);
+	if (scene == NULL)
+		return;
+	redraw_set_draw_context(&dctx, scene);
+	redraw_get_window_offset(c, &ox, &oy, &sx, &sy);
+
+	TAILQ_FOREACH(wp, &w->panes, entry) {
+		wp->border_gc_set = 0;
+		wp->active_border_gc_set = 0;
+	}
+
+	tty_sync_start(&c->tty);
+	tty_update_mode(&c->tty, c->tty.mode & ~CURSOR_MODES, NULL);
+
+	TAILQ_FOREACH(rd, &w->damage, entry) {
+		x0 = (rd->x > ox) ? rd->x : ox;
+		y0 = (rd->y > oy) ? rd->y : oy;
+		x1 = (rd->x + rd->sx < ox + sx) ? rd->x + rd->sx : ox + sx;
+		y1 = (rd->y + rd->sy < oy + sy) ? rd->y + rd->sy : oy + sy;
+		if (x0 < x1 && y0 < y1) {
+			redraw_draw_damage_rectangle(&dctx, x0 - ox, y0 - oy,
+			    x1 - x0, y1 - y0);
+		}
+	}
+}

screen-write.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: screen-write.c,v 1.291 2026/09/21 10:22:31 nicm Exp $ */
+/* $OpenBSD: screen-write.c,v 1.293 2026/09/24 11:19:39 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -38,7 +38,9 @@ static int	screen_write_overwrite(struct screen_write_ctx *,
 		    struct grid_cell *, u_int);
 static int	screen_write_combine(struct screen_write_ctx *,
 		    const struct grid_cell *);
-static void	screen_write_flush_dirty(struct window_pane *);
+static void	screen_write_sync_flush_dirty(struct window_pane *);
+static void	screen_write_sync_apply_scroll(struct screen_write_ctx *,
+		    struct tty_ctx *);
 
 struct screen_write_citem {
 	u_int				x;
@@ -120,14 +122,26 @@ screen_write_set_cursor(struct screen_write_ctx *ctx, int cx, int cy)
 		evtimer_add(&w->offset_timer, &tv);
 }
 
-/* Do a full redraw. */
+/* Redraw lines. */
 static void
-screen_write_redraw_cb(const struct tty_ctx *ttyctx)
+screen_write_redraw_cb(const struct tty_ctx *ttyctx, u_int py, u_int ny)
 {
 	struct window_pane	*wp = ttyctx->arg;
+	int			 x0, y0, x1, y1;
 
-	if (wp != NULL)
-		wp->flags |= PANE_REDRAW;
+	if (wp == NULL)
+		return;
+
+	x0 = wp->xoff;
+	y0 = wp->yoff + (int)py;
+	x1 = x0 + (int)wp->sx;
+	y1 = y0 + (int)ny;
+	if (x0 < 0)
+		x0 = 0;
+	if (y0 < 0)
+		y0 = 0;
+	if (x1 > x0 && y1 > y0)
+		redraw_damage_window(wp->window, x0, y0, x1 - x0, y1 - y0);
 }
 
 /* Update context for client. */
@@ -215,6 +229,27 @@ screen_write_pane_is_obscured(struct screen_write_ctx *ctx)
 	return (0);
 }
 
+/* Allocate dirty lines for this screen size. */
+static bitstr_t *
+screen_write_sync_allocate_dirty(struct window_pane *wp, u_int sy)
+{
+	bitstr_t	*bs = wp->sync_dirty;
+
+	if (bs != NULL && wp->sync_dirty_size == sy)
+		return (bs);
+
+	free(bs);
+	bs = wp->sync_dirty = bit_alloc(sy);
+	if (bs == NULL)
+		fatal("bit_alloc failed");
+	if (wp->sync_dirty_size != 0) {
+		bit_nset(bs, 0, sy - 1);
+		wp->sync_scrolled = 0;
+	}
+	wp->sync_dirty_size = sy;
+	return (bs);
+}
+
 /* Should we draw to the TTY? */
 static int
 screen_write_should_draw_lines(struct screen_write_ctx *ctx, u_int y, u_int ny)
@@ -228,21 +263,9 @@ screen_write_should_draw_lines(struct screen_write_ctx *ctx, u_int y, u_int ny)
 		return (0);
 	if (s->mode & MODE_SYNC) {
 		if (wp != NULL && y < sy && ny != 0) {
-			bs = wp->sync_dirty;
 			if (ny > sy - y)
 				ny = sy - y;
-			if (bs == NULL || wp->sync_dirty_size != sy) {
-				if (bs != NULL && wp->sync_dirty_size != sy) {
-					y = 0;
-					ny = sy;
-				}
-				free(bs);
-
-				bs = wp->sync_dirty = bit_alloc(sy);
-				if (bs == NULL)
-					fatal("bit_alloc failed");
-				wp->sync_dirty_size = sy;
-			}
+			bs = screen_write_sync_allocate_dirty(wp, sy);
 			bit_nset(bs, y, y + ny - 1);
 		}
 		return (0);
@@ -833,34 +856,39 @@ screen_write_menu(struct screen_write_ctx *ctx, struct menu *menu, int choice,
 	struct screen		*s = ctx->s;
 	struct grid_cell	 default_gc;
 	const struct grid_cell	*gc = &default_gc;
-	u_int			 cx, cy, i, j, width = menu->width;
+	u_int			 border, cx = s->cx, cy = s->cy, i, j, width;
 	const char		*name;
 
-	cx = s->cx;
-	cy = s->cy;
-
 	memcpy(&default_gc, menu_gc, sizeof default_gc);
 
-	screen_write_box(ctx, menu->width + 4, menu->count + 2, lines,
-	    border_gc, menu->title);
+	if (lines == BOX_LINES_NONE) {
+		border = 0;
+		width = menu->item_width;
+	} else {
+		border = 1;
+		width = menu->width;
+		screen_write_box(ctx, width + 4, menu->count + 2, lines,
+		    border_gc, menu->title);
+	}
 
 	for (i = 0; i < menu->count; i++) {
 		name = menu->items[i].name;
 		if (name == NULL) {
-			screen_write_cursormove(ctx, cx, cy + 1 + i, 0);
-			screen_write_hline(ctx, width + 4, 1, 1, lines,
-			    border_gc);
+			screen_write_cursormove(ctx, cx, cy + border + i, 0);
+			screen_write_hline(ctx, width + 2 + (2 * border), 1, 1,
+			    lines, border_gc);
 			continue;
 		}
 
 		if (choice >= 0 && i == (u_int)choice && *name != '-')
 			gc = choice_gc;
 
-		screen_write_cursormove(ctx, cx + 1, cy + 1 + i, 0);
+		screen_write_cursormove(ctx, cx + border, cy + border + i, 0);
 		for (j = 0; j < width + 2; j++)
 			screen_write_putc(ctx, gc, ' ');
 
-		screen_write_cursormove(ctx, cx + 2, cy + 1 + i, 0);
+		screen_write_cursormove(ctx, cx + border + 1, cy + border + i,
+		    0);
 		if (*name == '-') {
 			default_gc.attr |= GRID_ATTR_DIM;
 			format_draw(ctx, gc, width, name + 1, NULL, 0);
@@ -1027,7 +1055,7 @@ screen_write_sync_callback(__unused int fd, __unused short events, void *arg)
 
 	if (wp->base.mode & MODE_SYNC) {
 		wp->base.mode &= ~MODE_SYNC;
-		screen_write_flush_dirty(wp);
+		screen_write_sync_flush_dirty(wp);
 	}
 }
 
@@ -1059,7 +1087,7 @@ screen_write_stop_sync(struct window_pane *wp)
 		evtimer_del(&wp->sync_timer);
 	wp->base.mode &= ~MODE_SYNC;
 
-	screen_write_flush_dirty(wp);
+	screen_write_sync_flush_dirty(wp);
 
 	log_debug("%s: %%%u stopped sync mode", __func__, wp->id);
 }
@@ -1267,7 +1295,7 @@ screen_write_redraw_line(struct screen_write_ctx *ctx, struct tty_ctx *ttyctx,
 
 /* Redraw dirty lines. */
 static void
-screen_write_flush_dirty(struct window_pane *wp)
+screen_write_sync_flush_dirty(struct window_pane *wp)
 {
 	struct screen_write_ctx	 ctx;
 	struct tty_ctx		 ttyctx;
@@ -1280,29 +1308,143 @@ screen_write_flush_dirty(struct window_pane *wp)
 	screen_write_start_pane(&ctx, wp, s);
 	screen_write_initctx(&ctx, &ttyctx, 1, 1);
 
-	for (y = 0; y < sy; y++) {
-		if (bit_test(wp->sync_dirty, y)) {
-			screen_write_redraw_line(&ctx, &ttyctx, y);
-			lines++;
+	if (wp->sync_scrolled != 0)
+		screen_write_sync_apply_scroll(&ctx, &ttyctx);
+
+	if (~wp->flags & PANE_REDRAW) {
+		for (y = 0; y < sy; y++) {
+			if (bit_test(wp->sync_dirty, y)) {
+				screen_write_redraw_line(&ctx, &ttyctx, y);
+				lines++;
+			}
 		}
 	}
 	log_debug("%s: %%%u had %u dirty lines", __func__, wp->id, lines);
 
 	screen_write_stop(&ctx);
-	screen_write_clear_dirty(wp);
+	screen_write_sync_clear_dirty(wp);
 }
 
-/* Clear any dirty lines. */
+/* Clear pending synchronized output. */
 void
-screen_write_clear_dirty(struct window_pane *wp)
+screen_write_sync_clear_dirty(struct window_pane *wp)
 {
-	if (wp != NULL && wp->sync_dirty != NULL) {
+	if (wp != NULL) {
 		free(wp->sync_dirty);
 		wp->sync_dirty = NULL;
 		wp->sync_dirty_size = 0;
+		wp->sync_scrolled = 0;
 	}
 }
 
+/* Defer scrolling until the synchronized update ends. */
+static void
+screen_write_sync_scroll_dirty(struct screen_write_ctx *ctx)
+{
+	struct window_pane	*wp = ctx->wp;
+	struct screen		*s = ctx->s;
+	u_int			 n = ctx->scrolled, y, sy = screen_size_y(s);
+	u_int			 ry = s->rlower + 1 - s->rupper;
+	bitstr_t		*bs;
+
+	if (n > ry)
+		n = ry;
+	if (wp == NULL ||
+	    n == ry ||
+	    s->rlower >= sy ||
+	    window_pane_scrollbar_overlay_visible(wp)) {
+		screen_write_should_draw_lines(ctx, s->rupper, ry);
+		return;
+	}
+	if (wp->flags & (PANE_REDRAW|PANE_DROP))
+		return;
+	bs = screen_write_sync_allocate_dirty(wp, sy);
+
+	if (wp->sync_scrolled != 0 &&
+	    (wp->sync_rupper != s->rupper ||
+	    wp->sync_rlower != s->rlower ||
+	    wp->sync_bg != ctx->bg)) {
+		log_debug("%s: %%%u region changed, redrawing all", __func__,
+		    wp->id);
+		bit_nset(bs, 0, sy - 1);
+		wp->sync_scrolled = 0;
+		return;
+	}
+
+	/* Keep dirty lines aligned with the scrolled grid. */
+	for (y = s->rupper; y + n <= s->rlower; y++) {
+		if (bit_test(bs, y + n))
+			bit_set(bs, y);
+		else
+			bit_clear(bs, y);
+	}
+	bit_nset(bs, s->rlower + 1 - n, s->rlower);
+
+	wp->sync_rupper = s->rupper;
+	wp->sync_rlower = s->rlower;
+	wp->sync_bg = ctx->bg;
+	wp->sync_scrolled += n;
+	if (wp->sync_scrolled >= ry) {
+		bit_nset(bs, s->rupper, s->rlower);
+		wp->sync_scrolled = 0;
+	}
+	window_pane_scrollbar_redraw(wp);
+
+	log_debug("%s: %%%u deferred scroll of %u (region %u-%u)", __func__,
+	    wp->id, wp->sync_scrolled, s->rupper, s->rlower);
+}
+
+/* Redraw the scrolled lines for a client which cannot scroll them. */
+static void
+screen_write_sync_redraw_cb(const struct tty_ctx *ttyctx)
+{
+	struct window_pane	*wp = ttyctx->arg;
+
+	bit_nset(wp->sync_dirty, wp->sync_rupper, wp->sync_rlower);
+}
+
+/* Send the deferred scroll to the client. */
+static void
+screen_write_sync_apply_scroll(struct screen_write_ctx *ctx,
+    struct tty_ctx *ttyctx)
+{
+	struct window_pane	*wp = ctx->wp;
+	struct screen		*s = ctx->s;
+	u_int			 sy = screen_size_y(s), n = wp->sync_scrolled;
+	tty_ctx_redraw_cb	 redraw_cb;
+
+	wp->sync_scrolled = 0;
+	if (wp->flags & PANE_REDRAW)
+		return;
+	if (wp->sync_rlower >= sy || wp->sync_rupper > wp->sync_rlower) {
+		bit_nset(wp->sync_dirty, 0, sy - 1);
+		return;
+	}
+	if ((ttyctx->flags & TTY_CTX_PANE_OBSCURED) ||
+	    window_pane_scrollbar_overlay_visible(wp)) {
+		bit_nset(wp->sync_dirty, wp->sync_rupper, wp->sync_rlower);
+		return;
+	}
+
+	log_debug("%s: %%%u scroll of %u (region %u-%u)", __func__, wp->id, n,
+	    wp->sync_rupper, wp->sync_rlower);
+
+	ttyctx->orupper = wp->sync_rupper;
+	ttyctx->orlower = wp->sync_rlower;
+	if (wp->yoff + wp->sy > wp->window->sy)
+		ttyctx->orlower -= (wp->yoff + wp->sy - wp->window->sy);
+	ttyctx->n = n;
+	ttyctx->bg = wp->sync_bg;
+	redraw_cb = ttyctx->redraw_cb;
+	ttyctx->redraw_cb = screen_write_sync_redraw_cb;
+	tty_write(tty_cmd_scrollup, ttyctx);
+
+	ttyctx->redraw_cb = redraw_cb;
+	ttyctx->orupper = s->rupper;
+	ttyctx->orlower = s->rlower;
+	ttyctx->n = 0;
+}
+
 /* Redraw all visible cells in a pane. */
 static void
 screen_write_redraw_pane(struct screen_write_ctx *ctx, struct tty_ctx *ttyctx)
@@ -2150,7 +2292,7 @@ screen_write_fullredraw(struct screen_write_ctx *ctx)
 
 	screen_write_initctx(ctx, &ttyctx, 1, 0);
 	if (ttyctx.redraw_cb != NULL)
-		ttyctx.redraw_cb(&ttyctx);
+		ttyctx.redraw_cb(&ttyctx, 0, ttyctx.sy);
 }
 
 /* Trim collected items. */
@@ -2422,10 +2564,8 @@ screen_write_collect_flush(struct screen_write_ctx *ctx, int scroll_only,
 	if (wp != NULL && (wp->flags & (PANE_REDRAW|PANE_DROP)))
 		goto discard;
 	if (s->mode & MODE_SYNC) {
-		if (ctx->scrolled != 0) {
-			screen_write_should_draw_lines(ctx, s->rupper,
-			    s->rlower + 1 - s->rupper);
-		}
+		if (ctx->scrolled != 0)
+			screen_write_sync_scroll_dirty(ctx);
 		for (y = 0; y < screen_size_y(s); y++) {
 			cl = &s->write_list[y];
 			if (!TAILQ_EMPTY(&cl->items))
@@ -3170,7 +3310,7 @@ screen_write_alternateon(struct screen_write_ctx *ctx, struct grid_cell *gc,
 
 	screen_write_initctx(ctx, &ttyctx, 1, 0);
 	if (ttyctx.redraw_cb != NULL)
-		ttyctx.redraw_cb(&ttyctx);
+		ttyctx.redraw_cb(&ttyctx, 0, ttyctx.sy);
 }
 
 /* Turn alternate screen off. */
@@ -3195,5 +3335,5 @@ screen_write_alternateoff(struct screen_write_ctx *ctx, struct grid_cell *gc,
 
 	screen_write_initctx(ctx, &ttyctx, 1, 0);
 	if (ttyctx.redraw_cb != NULL)
-		ttyctx.redraw_cb(&ttyctx);
+		ttyctx.redraw_cb(&ttyctx, 0, ttyctx.sy);
 }

server-client.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: server-client.c,v 1.513 2026/09/21 10:22:31 nicm Exp $ */
+/* $OpenBSD: server-client.c,v 1.514 2026/09/22 06:46:50 nicm Exp $ */
 
 /*
  * Copyright (c) 2009 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -356,7 +356,13 @@ server_client_set_session(struct client *c, struct session *s)
 		tty_update_client_offset(c);
 		status_timer_start(c);
 		server_client_fire_session_changed(c, old);
-		server_redraw_client(c);
+
+		/*
+		 * Redraw if the session or displayed window changed. Use the
+		 * cached scene because the session's current window is already set.
+		 */
+		if (old != s || !redraw_client_has_window(c, s->curw->window))
+			server_redraw_client(c);
 	}
 
 	server_check_unattached();
@@ -384,6 +390,9 @@ server_client_lost(struct client *c)
 	TAILQ_REMOVE(&clients, c, entry);
 	log_debug("lost client %p", c);
 
+	cmd_wait_for_client_lost(c);
+	cmdq_next(c);
+
 	if (c->flags & CLIENT_ATTACHED) {
 		server_client_attached_lost(c);
 		events_fire_client("client-detached", c);
@@ -1346,10 +1355,11 @@ server_client_key_callback(struct cmdq_item *item, void *data)
 		m->key = key;
 
 		/*
-		 * Mouse drag is in progress, so fire the callback (now that
-		 * the mouse event is valid).
+		 * Synchronize direct drag output with the later damage redraw
+		 * before invoking the drag callback.
 		 */
 		if ((key & KEYC_MASK_KEY) == KEYC_DRAGGING) {
+			tty_sync_start(&c->tty);
 			c->tty.mouse_drag_update(c, m);
 			goto out;
 		}
@@ -1776,8 +1786,8 @@ server_client_loop(void)
 	}
 
 	/*
-	 * Any windows will have been redrawn as part of clients, so clear
-	 * their flags now.
+	 * Clear window redraw state after processing all clients. Deferred
+	 * redraws are preserved in client flags.
 	 */
 	RB_FOREACH(w, windows, &windows) {
 		TAILQ_FOREACH(wp, &w->panes, entry) {
@@ -1788,6 +1798,8 @@ server_client_loop(void)
 			wp->flags &= ~(PANE_REDRAW|PANE_REDRAWSCROLLBAR|
 			    PANE_ACTIVITY);
 		}
+		redraw_free_damage(w);
+
 		check_window_name(w);
 	}
 
@@ -2333,6 +2345,8 @@ server_client_any_pane_redraw(struct client *c)
 
 	if (c->flags & CLIENT_REDRAWWINDOW)
 		return (1);
+	if (!TAILQ_EMPTY(&w->damage))
+		return (1);
 	TAILQ_FOREACH(wp, &w->panes, entry) {
 		if (wp->flags & (PANE_REDRAW|PANE_REDRAWSCROLLBAR))
 			return (1);
@@ -2349,6 +2363,7 @@ server_client_check_redraw(struct client *c)
 	struct window		*w = s->curw->window;
 	struct window_pane	*wp;
 	int			 needed, tflags, mode = tty->mode;
+	int			 damaged = !TAILQ_EMPTY(&w->damage);
 	struct timeval		 tv = { .tv_usec = 1000 };
 	static struct event	 ev;
 	size_t			 n;
@@ -2374,12 +2389,12 @@ server_client_check_redraw(struct client *c)
 		return;
 	}
 
-	/*
-	 * If there is outstanding data, defer the redraw until it has been
-	 * consumed. We can just add a timer to get out of the event loop and
-	 * end up back here.
-	 */
+	/* Ignore output queued within the current synchronized frame. */
 	n = EVBUFFER_LENGTH(tty->out);
+	if ((tty->flags & TTY_SYNCING) && n > tty->sync_offset)
+		n = tty->sync_offset;
+
+	/* Defer until output drains, preserving damage in client flags. */
 	if (n != 0 || (tty->flags & TTY_BLOCK)) {
 		if (n != 0)
 			log_debug("%s: redraw deferred (%zu left)", c->name, n);
@@ -2391,6 +2406,10 @@ server_client_check_redraw(struct client *c)
 			log_debug("redraw timer started");
 			evtimer_add(&ev, &tv);
 		}
+		if (damaged) {
+			c->flags |= CLIENT_REDRAWWINDOW;
+			return;
+		}
 		TAILQ_FOREACH(wp, &w->panes, entry) {
 			if (wp->flags & PANE_REDRAW) {
 				c->flags |= CLIENT_REDRAWWINDOW;
@@ -2424,6 +2443,10 @@ server_client_check_redraw(struct client *c)
 				redraw_pane_scrollbar(c, wp);
 			}
 		}
+
+		/* Draw damage here if no client redraw flags will handle it. */
+		if (damaged && (c->flags & CLIENT_ALLREDRAWFLAGS) == 0)
+			redraw_client_damage(c);
 	}
 
 	/*
@@ -2437,6 +2460,7 @@ server_client_check_redraw(struct client *c)
 		}
 		server_client_set_progress_bar(c);
 		redraw_screen(c);
+		redraw_client_damage(c);
 	}
 
 	/* Put the tty back how it was. */

server-fn.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: server-fn.c,v 1.153 2026/09/10 11:02:18 nicm Exp $ */
+/* $OpenBSD: server-fn.c,v 1.154 2026/09/21 12:43:36 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -310,8 +310,8 @@ server_link_window(struct session *src, struct winlink *srcwl,
 		}
 		if (killflag) {
 			/*
-			 * Can't use session_detach as it will destroy session
-			 * if this makes it empty.
+			 * Can't use session_detach as it won't detach the only
+			 * window.
 			 */
 			events_fire_winlink("window-unlinked", dstwl);
 			dstwl->flags &= ~WINLINK_ALERTFLAGS;

session.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: session.c,v 1.107 2026/08/05 07:35:35 nicm Exp $ */
+/* $OpenBSD: session.c,v 1.108 2026/09/21 12:43:36 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -336,10 +336,17 @@ session_attach(struct session *s, struct window *w, int idx, char **cause)
 	return (wl);
 }
 
-/* Detach a window from a session. */
+/*
+ * Detach a window from a session. Returns 1 if the window has not been
+ * detached - the caller must destroy the session.
+ */
 int
 session_detach(struct session *s, struct winlink *wl)
 {
+	if (RB_MIN(winlinks, &s->windows) == wl &&
+	    RB_MAX(winlinks, &s->windows) == wl)
+		return (1);
+
 	if (s->curw == wl &&
 	    session_last(s) != 0 &&
 	    session_previous(s, 0) != 0)
@@ -352,8 +359,6 @@ session_detach(struct session *s, struct winlink *wl)
 
 	session_group_synchronize_from(s);
 
-	if (RB_EMPTY(&s->windows))
-		return (1);
 	return (0);
 }
 

spawn.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: spawn.c,v 1.52 2026/08/20 09:19:24 nicm Exp $ */
+/* $OpenBSD: spawn.c,v 1.53 2026/09/21 12:43:36 nicm Exp $ */
 
 /*
  * Copyright (c) 2019 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -166,8 +166,8 @@ spawn_window(struct spawn_context *sc, char **cause)
 		}
 		if (wl != NULL) {
 			/*
-			 * Can't use session_detach as it will destroy session
-			 * if this makes it empty.
+			 * Can't use session_detach as it won't detach the only
+			 * window.
 			 */
 			wl->flags &= ~WINLINK_ALERTFLAGS;
 			events_fire_winlink("window-unlinked", wl);

tmux.1

@@ -1,4 +1,4 @@
-.\" $OpenBSD: tmux.1,v 1.1171 2026/09/21 10:22:31 nicm Exp $
+.\" $OpenBSD: tmux.1,v 1.1173 2026/09/23 12:37:50 nicm Exp $
 .\"
 .\" Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
 .\"
@@ -14,7 +14,7 @@
 .\" IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 .\" OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: September 21 2026 $
+.Dd $Mdocdate: September 23 2026 $
 .Dt TMUX 1
 .Os
 .Sh NAME
@@ -994,13 +994,19 @@ Will run:
 /bin/sh \-c \[aq]vi \[ti]/.tmux.conf\[aq]
 .Ed
 .Pp
+Unless specified, tmux uses the value of
+.Ic default\-shell
+in place of
+.Pa /bin/sh .
+.Pp
 Additionally, the
 .Ic new\-window ,
 .Ic new\-session ,
 .Ic split\-window ,
-.Ic respawn\-window
-and
+.Ic respawn\-window ,
 .Ic respawn\-pane
+and
+.Ic display\-popup
 commands allow
 .Ar shell\-command
 to be given as multiple arguments and executed directly (without
@@ -5085,6 +5091,9 @@ The available features are:
 .Bl -tag -width Ds
 .It 256
 Supports 256 colours with the SGR escape sequences.
+.It appesc
+Supports application escape key mode, where the Escape key sends a sequence
+that cannot be mistaken for the start of another key.
 .It clipboard
 Allows setting the system clipboard.
 .It ccolour
@@ -8833,6 +8842,8 @@ These are set automatically if the
 capability is present.
 .It Em \&Dseks , \&Eneks
 Disable and enable extended keys.
+.It Em \&Dsesc , \&Enesc
+Disable and enable application escape key mode.
 .It Em \&Dsfcs , \&Enfcs
 Disable and enable focus reporting.
 These are set automatically if the

tmux.h

@@ -1,4 +1,4 @@
-/* $OpenBSD: tmux.h,v 1.1442 2026/09/21 10:22:31 nicm Exp $ */
+/* $OpenBSD: tmux.h,v 1.1448 2026/09/24 11:19:39 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -69,6 +69,7 @@ struct options_array_item;
 struct options_entry;
 struct prompt;
 struct window_pane_prompt;
+struct redraw_damage;
 struct redraw_scene;
 struct redraw_span;
 struct screen_write_citem;
@@ -464,6 +465,7 @@ enum tty_code_code {
 	TTYC_DL1,
 	TTYC_DSBP,
 	TTYC_DSEKS,
+	TTYC_DSESC,
 	TTYC_DSFCS,
 	TTYC_DSMG,
 	TTYC_E3,
@@ -474,6 +476,7 @@ enum tty_code_code {
 	TTYC_ENACS,
 	TTYC_ENBP,
 	TTYC_ENEKS,
+	TTYC_ENESC,
 	TTYC_ENFCS,
 	TTYC_ENMG,
 	TTYC_FSL,
@@ -1182,6 +1185,7 @@ struct menu {
 	struct menu_item	*items;
 	u_int			 count;
 	u_int			 width;
+	u_int			 item_width;
 };
 typedef void (*menu_choice_cb)(struct menu *, u_int, key_code, void *);
 
@@ -1344,6 +1348,10 @@ struct window_pane {
 
 	bitstr_t	*sync_dirty;
 	u_int		 sync_dirty_size;
+	u_int		 sync_scrolled;
+	u_int		 sync_rupper;
+	u_int		 sync_rlower;
+	u_int		 sync_bg;
 
 	u_int		 sb_slider_y;
 	u_int		 sb_slider_h;
@@ -1399,6 +1407,7 @@ struct window_pane {
 	struct screen	 base;
 
 	struct screen	 status_screen;
+	u_int		 status_generation;
 
 	TAILQ_HEAD(, window_mode_entry) modes;
 
@@ -1429,6 +1438,7 @@ struct window_pane {
 TAILQ_HEAD(window_panes, window_pane);
 TAILQ_HEAD(window_panes_zindex, window_pane);
 RB_HEAD(window_pane_tree, window_pane);
+TAILQ_HEAD(redraw_damages, redraw_damage);
 
 /* Window structure. */
 struct window {
@@ -1472,6 +1482,9 @@ struct window {
 
 	uint64_t		 redraw_scene_generation;
 
+	struct redraw_damages	 damage;
+	u_int			 damage_count;
+
 	struct menu_data	*menu;
 	u_int			 menu_last_px;
 	u_int			 menu_last_py;
@@ -1739,6 +1752,7 @@ struct tty_term {
 #define TERM_VT100LIKE 0x20
 #define TERM_SIXEL 0x40
 #define TERM_INVALIDMS 0x80
+#define TERM_NOREPLACE 0x100
 	int		 flags;
 
 	LIST_ENTRY(tty_term) entry;
@@ -1796,6 +1810,8 @@ struct tty {
 	struct event	 timer;
 	size_t		 discarded;
 
+	size_t		 sync_offset;
+
 	struct termios	 tio;
 
 	struct grid_cell cell;
@@ -1843,7 +1859,7 @@ struct tty {
 };
 
 /* Terminal command context. */
-typedef void (*tty_ctx_redraw_cb)(const struct tty_ctx *);
+typedef void (*tty_ctx_redraw_cb)(const struct tty_ctx *, u_int, u_int);
 typedef int (*tty_ctx_set_client_cb)(struct tty_ctx *, struct client *);
 struct tty_ctx {
 	struct screen		*s;
@@ -2984,7 +3000,7 @@ void	tty_default_colours(struct grid_cell *, struct window_pane *, u_int *);
 /* tty-term.c */
 extern struct tty_terms tty_terms;
 u_int		 tty_term_ncodes(void);
-void		 tty_term_apply(struct tty_term *, const char *, int);
+void		 tty_term_apply(struct tty_term *, const char *, int, int);
 void		 tty_term_apply_overrides(struct tty_term *);
 struct tty_term *tty_term_create(struct tty *, char *, char **, u_int, char **);
 void		 tty_term_free(struct tty_term *);
@@ -3204,6 +3220,7 @@ void 		 cmdq_print_data(struct cmdq_item *, struct evbuffer *);
 void printflike(2, 3) cmdq_error(struct cmdq_item *, const char *, ...);
 
 /* cmd-wait-for.c */
+void	cmd_wait_for_client_lost(struct client *);
 void	cmd_wait_for_flush(void);
 
 /* client.c */
@@ -3581,7 +3598,7 @@ void	 screen_write_mode_clear(struct screen_write_ctx *, int);
 void	 screen_write_start_sync(struct window_pane *);
 void	 screen_write_stop_sync(struct window_pane *);
 void	 screen_write_end_sync(struct screen_write_ctx *);
-void	 screen_write_clear_dirty(struct window_pane *);
+void	 screen_write_sync_clear_dirty(struct window_pane *);
 void	 screen_write_cursorup(struct screen_write_ctx *, u_int);
 void	 screen_write_cursordown(struct screen_write_ctx *, u_int);
 void	 screen_write_cursorright(struct screen_write_ctx *, u_int);
@@ -3629,8 +3646,12 @@ void	 redraw_screen(struct client *);
 void	 redraw_pane(struct client *, struct window_pane *);
 void	 redraw_pane_scrollbar(struct client *, struct window_pane *);
 void	 redraw_free_scene(struct redraw_scene *);
+int	 redraw_client_has_window(struct client *, struct window *);
 void	 redraw_invalidate_scene(struct window *);
 void	 redraw_invalidate_all_scenes(void);
+void	 redraw_damage_window(struct window *, u_int, u_int, u_int, u_int);
+void	 redraw_free_damage(struct window *);
+void	 redraw_client_damage(struct client *);
 int	 redraw_get_status_border_cell_type(struct redraw_span **, u_int);
 
 /* screen.c */
@@ -3804,6 +3825,9 @@ int		 window_pane_get_pane_status(struct window_pane *);
 struct style_range *window_pane_status_get_range(struct window_pane *, u_int,
 		     u_int);
 int		 window_pane_is_floating(struct window_pane *);
+int		 window_pane_is_floating_with_hidden(struct window_pane *);
+void		 window_redraw_floating_pane(struct window_pane *, int, int,
+		     int, int);
 
 /* window-border.c */
 void		 window_set_fill_cells(struct window *);
@@ -4143,6 +4167,7 @@ void		 menu_add_item(struct menu *, const struct menu_item *,
 		    struct cmdq_item *, struct client *,
 		    struct cmd_find_state *);
 void		 menu_free(struct menu *);
+void		 menu_get_size(struct menu *, enum box_lines, u_int *, u_int *);
 int		 menu_display(struct menu *, int, int, struct cmdq_item *,
 		    u_int, u_int, struct client *, enum box_lines, const char *,
 		    const char *, const char *, struct cmd_find_state *,

tty-draw.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: tty-draw.c,v 1.16 2026/09/21 10:22:31 nicm Exp $ */
+/* $OpenBSD: tty-draw.c,v 1.17 2026/09/22 06:49:47 nicm Exp $ */
 
 /*
  * Copyright (c) 2026 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -218,7 +218,12 @@ tty_draw_line(struct tty *tty, struct screen *s, u_int px, u_int py, u_int nx,
 	}
 
 	/* Did the previous line wrap on to this one? */
-	if (py != 0 && atx == 0 && tty->cx >= tty->sx && nx == tty->sx) {
+	if (py != 0 &&
+	    atx == 0 &&
+	    tty->cx >= tty->sx &&
+	    tty->cy != UINT_MAX &&
+	    tty->cy + 1 == aty &&
+	    nx == tty->sx) {
 		gl = grid_get_line(gd, gd->hsize + py - 1);
 		if (gl->flags & GRID_LINE_WRAPPED)
 			wrapped = 1;

tty-features.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: tty-features.c,v 1.43 2026/08/31 12:41:03 kirill Exp $ */
+/* $OpenBSD: tty-features.c,v 1.46 2026/09/24 08:16:13 nicm Exp $ */
 
 /*
  * Copyright (c) 2020 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -189,6 +189,18 @@ static const struct tty_feature tty_feature_focus = {
 	0
 };
 
+/* Terminal supports application escape key mode. */
+static const char *const tty_feature_appesc_capabilities[] = {
+	"Enesc=\\E[?7727h",
+	"Dsesc=\\E[?7727l",
+	NULL
+};
+static const struct tty_feature tty_feature_appesc = {
+	"appesc",
+	tty_feature_appesc_capabilities,
+	0
+};
+
 /* Terminal supports cursor styles. */
 static const char *const tty_feature_cstyle_capabilities[] = {
 	"Ss=\\E[%p1%d q",
@@ -198,7 +210,7 @@ static const char *const tty_feature_cstyle_capabilities[] = {
 static const struct tty_feature tty_feature_cstyle = {
 	"cstyle",
 	tty_feature_cstyle_capabilities,
-	0
+	TERM_NOREPLACE
 };
 
 /* Terminal supports cursor colours. */
@@ -378,6 +390,7 @@ static const struct tty_feature tty_feature_utf8 = {
 /* Available terminal features. */
 static const struct tty_feature *const tty_features[] = {
 	&tty_feature_256,
+	&tty_feature_appesc,
 	&tty_feature_bpaste,
 	&tty_feature_ccolour,
 	&tty_feature_clipboard,
@@ -541,11 +554,11 @@ tty_apply_features(struct tty_term *term)
 			capability = tf->capabilities;
 			while (*capability != NULL) {
 				log_debug("adding capability: %s", *capability);
-				tty_term_apply(term, *capability, 1);
+				tty_term_apply(term, *capability, 1, tf->flags);
 				capability++;
 			}
 		}
-		term->flags |= tf->flags;
+		term->flags |= (tf->flags & ~TERM_NOREPLACE);
 		if (tf == &tty_feature_utf8)
 			c->flags |= CLIENT_UTF8;
 	}
@@ -568,6 +581,7 @@ tty_default_features(struct client *c, const char *name, u_int version)
 	"256,RGB,bpaste,clipboard,mouse,strikethrough,title"
 		{ .name = "mintty",
 		  .features = TTY_FEATURES_BASE_MODERN_XTERM ","
+			      "appesc,"
 			      "ccolour,"
 			      "cstyle,"
 			      "extkeys,"
@@ -623,6 +637,7 @@ tty_default_features(struct client *c, const char *name, u_int version)
 			      "extkeys,"
 			      "focus,"
 		  	      "hyperlinks,"
+			      "margins,"
 			      "usstyle"
 		},
 		{ .name = "ghostty",
@@ -631,6 +646,7 @@ tty_default_features(struct client *c, const char *name, u_int version)
 			      "cstyle,"
 			      "extkeys,"
 			      "focus,"
+			      "margins,"
 			      "overline,"
 			      "hyperlinks,"
 			      "osc7,"
@@ -661,7 +677,7 @@ tty_default_features(struct client *c, const char *name, u_int version)
 			      "cstyle,"
 			      "extkeys,"
 			      "focus"
-		}
+		},
 	};
 	u_int	i;
 

tty-term.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: tty-term.c,v 1.109 2026/08/25 08:37:08 nicm Exp $ */
+/* $OpenBSD: tty-term.c,v 1.111 2026/09/22 14:10:26 nicm Exp $ */
 
 /*
  * Copyright (c) 2008 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -90,6 +90,7 @@ static const struct tty_term_code_entry tty_term_codes[] = {
 	[TTYC_DL1] = { TTYCODE_STRING, "dl1" },
 	[TTYC_DL] = { TTYCODE_STRING, "dl" },
 	[TTYC_DSEKS] = { TTYCODE_STRING, "Dseks" },
+	[TTYC_DSESC] = { TTYCODE_STRING, "Dsesc" },
 	[TTYC_DSFCS] = { TTYCODE_STRING, "Dsfcs" },
 	[TTYC_DSBP] = { TTYCODE_STRING, "Dsbp" },
 	[TTYC_DSMG] = { TTYCODE_STRING, "Dsmg" },
@@ -101,6 +102,7 @@ static const struct tty_term_code_entry tty_term_codes[] = {
 	[TTYC_ENACS] = { TTYCODE_STRING, "enacs" },
 	[TTYC_ENBP] = { TTYCODE_STRING, "Enbp" },
 	[TTYC_ENEKS] = { TTYCODE_STRING, "Eneks" },
+	[TTYC_ENESC] = { TTYCODE_STRING, "Enesc" },
 	[TTYC_ENFCS] = { TTYCODE_STRING, "Enfcs" },
 	[TTYC_ENMG] = { TTYCODE_STRING, "Enmg" },
 	[TTYC_FSL] = { TTYCODE_STRING, "fsl" },
@@ -362,7 +364,8 @@ tty_term_override_next(const char *s, size_t *offset)
 }
 
 void
-tty_term_apply(struct tty_term *term, const char *capabilities, int quiet)
+tty_term_apply(struct tty_term *term, const char *capabilities, int quiet,
+    int flags)
 {
 	const struct tty_term_code_entry	*ent;
 	struct tty_code				*code;
@@ -405,6 +408,9 @@ tty_term_apply(struct tty_term *term, const char *capabilities, int quiet)
 			if (strcmp(s, ent->name) != 0)
 				continue;
 			code = &term->codes[i];
+			if ((flags & TERM_NOREPLACE) &&
+			    code->type != TTYCODE_NONE)
+				continue;
 
 			if (remove) {
 				code->type = TTYCODE_NONE;
@@ -457,7 +463,7 @@ tty_term_apply_overrides(struct tty_term *term)
 		offset = 0;
 		first = tty_term_override_next(s, &offset);
 		if (first != NULL && fnmatch(first, term->name, 0) == 0)
-			tty_term_apply(term, s + offset, 0);
+			tty_term_apply(term, s + offset, 0, 0);
 		a = options_array_next(a);
 	}
 

tty.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: tty.c,v 1.481 2026/09/21 10:22:31 nicm Exp $ */
+/* $OpenBSD: tty.c,v 1.482 2026/09/22 06:58:06 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -502,8 +502,7 @@ tty_stop_tty(struct tty *tty)
 	if (tty_term_has(tty->term, TTYC_DSBP))
 		tty_raw(tty, tty_term_string(tty->term, TTYC_DSBP));
 
-	if (tty->term->flags & TERM_VT100LIKE)
-		tty_raw(tty, "\033[?7727l");
+	tty_raw(tty, tty_term_string(tty->term, TTYC_DSESC));
 	tty_raw(tty, tty_term_string(tty->term, TTYC_DSFCS));
 	tty_raw(tty, tty_term_string(tty->term, TTYC_DSEKS));
 
@@ -560,8 +559,7 @@ tty_update_features(struct tty *tty)
 		tty_puts(tty, tty_term_string(tty->term, TTYC_ENEKS));
 	if (options_get_number(global_options, "focus-events"))
 		tty_puts(tty, tty_term_string(tty->term, TTYC_ENFCS));
-	if (tty->term->flags & TERM_VT100LIKE)
-		tty_puts(tty, "\033[?7727h");
+	tty_puts(tty, tty_term_string(tty->term, TTYC_ENESC));
 
 	/*
 	 * Features might have changed since the first draw during attach. For
@@ -1117,7 +1115,7 @@ tty_redraw_region(struct tty *tty, const struct tty_ctx *ctx)
 	 */
 	if (tty_large_region(tty, ctx) || ctx->flags & TTY_CTX_PANE_OBSCURED) {
 		log_debug("%s: %s large region redraw", __func__, c->name);
-		ctx->redraw_cb(ctx);
+		ctx->redraw_cb(ctx, ctx->orupper, ctx->orlower - ctx->orupper + 1);
 		return;
 	}
 
@@ -1519,6 +1517,7 @@ tty_sync_start(struct tty *tty)
 	if (tty->flags & TTY_SYNCING)
 		return;
 	tty->flags |= TTY_SYNCING;
+	tty->sync_offset = EVBUFFER_LENGTH(tty->out);
 
 	if (tty_term_has(tty->term, TTYC_SYNC)) {
 		log_debug("%s sync start", tty->client->name);
@@ -1925,7 +1924,7 @@ tty_cmd_alignmenttest(struct tty *tty, const struct tty_ctx *ctx)
 	u_int		 i, j;
 
 	if (ctx->flags & TTY_CTX_WINDOW_BIGGER) {
-		ctx->redraw_cb(ctx);
+		ctx->redraw_cb(ctx, 0, ctx->sy);
 		return;
 	}
 
@@ -1984,7 +1983,7 @@ tty_cmd_cells(struct tty *tty, const struct tty_ctx *ctx)
 		    tty->cy == tty->rlower)
 			tty_draw_pane(tty, ctx, ctx->ocy);
 		else
-			ctx->redraw_cb(ctx);
+			ctx->redraw_cb(ctx, ctx->ocy, 1);
 		return;
 	}
 

window-copy.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: window-copy.c,v 1.430 2026/09/21 10:22:31 nicm Exp $ */
+/* $OpenBSD: window-copy.c,v 1.431 2026/09/21 10:43:37 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -401,7 +401,7 @@ window_copy_clone_screen(struct screen *src, struct screen *hint, u_int *cx,
 
 	sy = screen_hsize(src) + screen_size_y(src);
 	if (trim) {
-		while (sy > screen_hsize(src)) {
+		while (sy > screen_hsize(src) + 1) {
 			gl = grid_peek_line(src->grid, sy - 1);
 			if (gl == NULL || gl->cellused != 0)
 				break;
@@ -768,6 +768,7 @@ window_copy_scroll(struct window_pane *wp, int sl_mpos, u_int my,
 	struct window_mode_entry	*wme = TAILQ_FIRST(&wp->modes);
 
 	if (wme != NULL) {
+		window_redraw_active_switch(wp->window, wp);
 		window_set_active_pane(wp->window, wp, 0);
 		window_copy_scroll1(wme, wp, sl_mpos, my, tty_oy, scroll_exit);
 	}

window.c

@@ -1,4 +1,4 @@
-/* $OpenBSD: window.c,v 1.376 2026/09/21 10:22:31 nicm Exp $ */
+/* $OpenBSD: window.c,v 1.378 2026/09/24 11:19:39 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -415,6 +415,7 @@ window_create(u_int sx, u_int sy, u_int xpixel, u_int ypixel)
 	TAILQ_INIT(&w->panes);
 	TAILQ_INIT(&w->z_index);
 	TAILQ_INIT(&w->last_panes);
+	TAILQ_INIT(&w->damage);
 	w->active = NULL;
 
 	w->lastlayout = -1;
@@ -468,6 +469,7 @@ window_destroy(struct window *w)
 
 	menu_destroy(w);
 	window_destroy_panes(w);
+	redraw_free_damage(w);
 
 	if (event_initialized(&w->name_event))
 		evtimer_del(&w->name_event);
@@ -718,6 +720,7 @@ int
 window_set_active_pane(struct window *w, struct window_pane *wp, int notify)
 {
 	struct window_pane *lastwp;
+	int		    unzoomed;
 
 	log_debug("%s: pane %%%u", __func__, wp->id);
 
@@ -725,7 +728,8 @@ window_set_active_pane(struct window *w, struct window_pane *wp, int notify)
 		return (0);
 	if (w->modal != NULL && wp != w->modal)
 		return (0);
-	if ((w->flags & WINDOW_ZOOMED) && !window_pane_is_visible(wp))
+	unzoomed = (w->flags & WINDOW_ZOOMED) && !window_pane_is_visible(wp);
+	if (unzoomed)
 		window_unzoom(w, 1);
 	lastwp = w->active;
 
@@ -742,7 +746,19 @@ window_set_active_pane(struct window *w, struct window_pane *wp, int notify)
 	}
 
 	tty_update_window_offset(w);
-	server_redraw_window(w);
+
+	/*
+	 * Unzooming changes every pane's geometry and needs a full window
+	 * redraw. Otherwise, only the previous and new active pane's border
+	 * and status appearance changed, so avoid redrawing unaffected pane
+	 * content.
+	 */
+	if (unzoomed)
+		server_redraw_window(w);
+	else {
+		server_redraw_window_borders(w);
+		server_status_window(w);
+	}
 
 	if (notify)
 		window_fire_pane_changed(w, w->active, lastwp);
@@ -1528,7 +1544,7 @@ window_pane_destroy(struct window_pane *wp)
 	window_pane_clear_prompt(wp);
 
 	window_pane_free_modes(wp);
-	screen_write_clear_dirty(wp);
+	screen_write_sync_clear_dirty(wp);
 
 	if (wp->fd != -1) {
 #ifdef HAVE_UTEMPTER
@@ -2913,3 +2929,52 @@ window_pane_is_floating(struct window_pane *wp)
 		return (0);
 	return (1);
 }
+
+int
+window_pane_is_floating_with_hidden(struct window_pane *wp)
+{
+	struct layout_cell	*lc = wp->layout_cell;
+
+	if (lc == NULL)
+		lc = wp->saved_layout_cell;
+	if (lc == NULL || (lc->flags & LAYOUT_CELL_FLOATING) == 0)
+		return (0);
+	return (1);
+}
+
+/* Report damage for a floating pane, including its border and scrollbar. */
+static void
+window_damage_floating_pane(struct window_pane *wp, int xoff, int yoff,
+    int sx, int sy)
+{
+	struct window	*w = wp->window;
+	int		 x0, x1, y0, y1, sb_left = 0, sb_right = 0;
+	struct style	*sb_sy = &wp->scrollbar_style;
+
+	if (window_pane_scrollbar_reserve(wp)) {
+		if (w->sb_pos == PANE_SCROLLBARS_LEFT)
+			sb_left = sb_sy->width + sb_sy->pad;
+		else
+			sb_right = sb_sy->width + sb_sy->pad;
+	}
+	x0 = xoff - 1 - sb_left;
+	x1 = xoff + sx + sb_right;
+	y0 = yoff - 1;
+	y1 = yoff + sy;
+	if (x0 < 0)
+		x0 = 0;
+	if (y0 < 0)
+		y0 = 0;
+	if (x1 >= x0 && y1 >= y0)
+		redraw_damage_window(w, x0, y0, x1 - x0 + 1U, y1 - y0 + 1U);
+}
+
+/* Report damage for a floating pane's old and new areas. */
+void
+window_redraw_floating_pane(struct window_pane *wp, int oxoff, int oyoff,
+    int osx, int osy)
+{
+	window_damage_floating_pane(wp, oxoff, oyoff, osx, osy);
+	window_damage_floating_pane(wp, wp->xoff, wp->yoff, wp->sx, wp->sy);
+	server_status_window(wp->window);
+}