diff --git a/regress/choose-buffer.sh b/regress/choose-buffer.sh
new file mode 100644
index 000000000..0f3e0d8da
--- /dev/null
+++ b/regress/choose-buffer.sh
@@ -0,0 +1,199 @@
+#!/bin/sh
+
+# Tests of buffer mode (window-buffer.c) as driven by choose-buffer: that the
+# -f filter removes buffers that do not match (by name and by content), that
+# a filter matching nothing falls back to showing everything, that -O and -r
+# change the sort order, that d deletes the selected buffer and C-t and D
+# delete all tagged buffers, and that Enter runs the default command
+# (paste-buffer) with the selected buffer.
+#
+# The list is drawn on a mode screen which capture-pane does not show, so 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. Each choose-buffer call uses a distinct -F marker so a
+# capture can be tied to the call it belongs to.
+
+PATH=/bin:/usr/bin
+TERM=screen
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+TMUX="$TEST_TMUX -Ltest -f/dev/null"
+TMUX2="$TEST_TMUX -Ltest2 -f/dev/null"
+
+cleanup()
+{
+	$TMUX kill-server 2>/dev/null
+	$TMUX2 kill-server 2>/dev/null
+}
+fail()
+{
+	echo "$1"
+	cleanup
+	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 $marker, so the
+# capture is known to show the mode instance under test.
+wait_for()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		if capture | grep -q "$1"; then
+			sleep 0.2
+			return 0
+		fi
+		sleep 0.2
+		i=$((i + 1))
+	done
+	fail "timed out waiting for '$1'"
+}
+
+# wait_buffers $n
+#
+# Wait (up to ~10s) until the test server has exactly $n paste buffers.
+wait_buffers()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		c=$($TMUX list-buffers -F x 2>/dev/null | grep -c x)
+		[ "$c" -eq "$1" ] && return 0
+		sleep 0.2
+		i=$((i + 1))
+	done
+	fail "expected $1 buffers, have $c"
+}
+
+# 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
+}
+
+$TMUX kill-server 2>/dev/null
+$TMUX2 kill-server 2>/dev/null
+
+$TMUX new-session -d -s aaa -x 80 -y 24 || exit 1
+
+$TMUX2 new-session -d -s out -x 80 -y 24 "$TMUX attach -t aaa" || exit 1
+wait_clients 1 || fail "no client attached to test server"
+
+# Two named buffers with distinct contents; bufa is created first.
+$TMUX set-buffer -b bufa "hello buffer" || exit 1
+$TMUX set-buffer -b bufz "other buffer" || exit 1
+
+# --- filter by buffer name ---------------------------------------------------
+$TMUX choose-buffer -t aaa:0 -F 'B1' -f '#{==:#{buffer_name},bufa}' || exit 1
+wait_for 'B1'
+out=$(capture)
+echo "$out" | grep -q 'bufa: B1' || fail "bufa missing when it matches"
+echo "$out" | grep -q 'bufz: B1' && fail "bufz shown but does not match"
+[ "$(echo "$out" | grep -c ': B1')" -eq 1 ] || fail "expected 1 buffer"
+$TMUX send-keys -t aaa:0 q
+
+# --- filter by buffer content ------------------------------------------------
+$TMUX choose-buffer -t aaa:0 -F 'B2' -f '#{m:*hello*,#{buffer_sample}}' || \
+	exit 1
+wait_for 'B2'
+out=$(capture)
+echo "$out" | grep -q 'bufa: B2' || fail "bufa missing when content matches"
+echo "$out" | grep -q 'bufz: B2' && fail "bufz shown but content not matched"
+$TMUX send-keys -t aaa:0 q
+
+# --- no filter shows both buffers ---------------------------------------------
+$TMUX choose-buffer -t aaa:0 -F 'B3' || exit 1
+wait_for 'B3'
+out=$(capture)
+echo "$out" | grep -q 'bufa: B3' || fail "bufa missing with no filter"
+echo "$out" | grep -q 'bufz: B3' || fail "bufz missing with no filter"
+[ "$(echo "$out" | grep -c ': B3')" -eq 2 ] || fail "expected 2 buffers"
+$TMUX send-keys -t aaa:0 q
+
+# --- filter matching nothing ---------------------------------------------------
+#
+# Everything is shown and the filter indicator reports no matches.
+$TMUX choose-buffer -t aaa:0 -F 'B4' -f '#{==:#{buffer_name},nosuch}' || \
+	exit 1
+wait_for 'B4'
+out=$(capture)
+echo "$out" | grep -q 'bufa: B4' || fail "bufa missing with no-match filter"
+echo "$out" | grep -q 'bufz: B4' || fail "bufz missing with no-match filter"
+echo "$out" | grep -q 'no matches' || fail "no matches indicator missing"
+$TMUX send-keys -t aaa:0 q
+
+# --- sort orders ---------------------------------------------------------------
+#
+# By name bufa sorts first and -r reverses.
+$TMUX choose-buffer -t aaa:0 -F 'B5' -O name || exit 1
+wait_for 'B5'
+capture | grep ': B5' | head -1 | grep -q 'bufa: B5' || \
+	fail "bufa not first with -O name"
+$TMUX send-keys -t aaa:0 q
+
+$TMUX choose-buffer -t aaa:0 -F 'B6' -O name -r || exit 1
+wait_for 'B6'
+capture | grep ': B6' | head -1 | grep -q 'bufz: B6' || \
+	fail "bufz not first with -O name -r"
+$TMUX send-keys -t aaa:0 q
+
+# --- d deletes the selected buffer --------------------------------------------
+#
+# The filter leaves only bufz listed and selected; d deletes it.
+$TMUX choose-buffer -t aaa:0 -F 'G1' -f '#{==:#{buffer_name},bufz}' || exit 1
+wait_for 'bufz: G1'
+$TMUX send-keys -t aaa:0 d
+wait_buffers 1
+$TMUX list-buffers -F '#{buffer_name}' | grep -q 'bufa' || \
+	fail "wrong buffer deleted"
+$TMUX send-keys -t aaa:0 q
+
+# --- C-t tags all buffers and D deletes the tagged ------------------------------
+$TMUX set-buffer -b bufz "other buffer" || exit 1
+$TMUX set-buffer -b bufb "third buffer" || exit 1
+$TMUX choose-buffer -t aaa:0 -F 'G2' || exit 1
+wait_for ': G2'
+$TMUX send-keys -t aaa:0 C-t D
+wait_buffers 0
+$TMUX send-keys -t aaa:0 q
+
+# --- Enter runs the default command (paste-buffer) ------------------------------
+#
+# The only buffer is listed and selected; Enter leaves the mode and pastes it
+# into the shell in the pane, where it appears on the screen.
+$TMUX set-buffer -b bufa "hello buffer" || exit 1
+$TMUX choose-buffer -t aaa:0 -F 'G3' || exit 1
+wait_for 'bufa: G3'
+$TMUX send-keys -t aaa:0 Enter
+i=0
+while [ "$i" -lt 50 ]; do
+	[ "$($TMUX display -p -t aaa:0 '#{pane_in_mode}')" = "0" ] && break
+	sleep 0.2
+	i=$((i + 1))
+done
+[ "$i" -lt 50 ] || fail "mode did not exit after Enter"
+i=0
+while [ "$i" -lt 50 ]; do
+	$TMUX capture-pane -p -t aaa:0 | grep -q 'hello buffer' && break
+	sleep 0.2
+	i=$((i + 1))
+done
+[ "$i" -lt 50 ] || fail "buffer not pasted into pane"
+
+cleanup
+exit 0
diff --git a/regress/choose-client.sh b/regress/choose-client.sh
new file mode 100644
index 000000000..e299b9852
--- /dev/null
+++ b/regress/choose-client.sh
@@ -0,0 +1,140 @@
+#!/bin/sh
+
+# Tests of client mode (window-client.c) as driven by choose-client: that the
+# -f filter removes clients that do not match, that a filter matching nothing
+# falls back to showing everything, and that Enter runs the default command
+# (detach-client) on the selected client. Sort orders are not tested here
+# because clients are named after their ttys, which are not predictable.
+#
+# The list is drawn on a mode screen which capture-pane does not show, so a
+# second server provides the clients: two inner "tmux attach" commands run in
+# panes of the second server, and the pane holding the client the mode is
+# displayed on is captured. Each choose-client call uses a distinct -F marker
+# so a capture can be tied to the call it belongs to.
+
+PATH=/bin:/usr/bin
+TERM=screen
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+TMUX="$TEST_TMUX -Ltest -f/dev/null"
+TMUX2="$TEST_TMUX -Ltest2 -f/dev/null"
+
+cleanup()
+{
+	$TMUX kill-server 2>/dev/null
+	$TMUX2 kill-server 2>/dev/null
+}
+fail()
+{
+	echo "$1"
+	cleanup
+	exit 1
+}
+
+# capture the screen rendered by the inner client attached to aaa
+capture()
+{
+	$TMUX2 capture-pane -p -t out:0 2>/dev/null
+}
+
+# wait_for $marker
+#
+# Wait (up to ~10s) until the rendered screen contains $marker, so the
+# capture is known to show the mode instance under test.
+wait_for()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		if capture | grep -q "$1"; then
+			sleep 0.2
+			return 0
+		fi
+		sleep 0.2
+		i=$((i + 1))
+	done
+	fail "timed out waiting for '$1'"
+}
+
+# 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
+}
+
+$TMUX kill-server 2>/dev/null
+$TMUX2 kill-server 2>/dev/null
+
+# One client attached to each of two sessions; the mode is displayed on the
+# client attached to aaa (in window 0 of the outer server) and the filters
+# tell the clients apart by their attached session.
+$TMUX new-session -d -s aaa -x 80 -y 24 || exit 1
+$TMUX new-session -d -s bbb -x 80 -y 24 || exit 1
+
+$TMUX2 new-session -d -s out -x 80 -y 24 "$TMUX attach -t aaa" || exit 1
+$TMUX2 new-window -d -t out: "$TMUX attach -t bbb" || exit 1
+wait_clients 2 || fail "expected two clients attached to test server"
+
+# --- filter keeping only the aaa client -------------------------------------
+$TMUX choose-client -t aaa:0 -F 'C1=#{client_session}' \
+	-f '#{==:#{client_session},aaa}' || exit 1
+wait_for 'C1='
+out=$(capture)
+echo "$out" | grep -q 'C1=aaa' || fail "aaa client missing when it matches"
+echo "$out" | grep -q 'C1=bbb' && fail "bbb client shown but does not match"
+[ "$(echo "$out" | grep -c 'C1=')" -eq 1 ] || fail "expected 1 client"
+$TMUX send-keys -t aaa:0 q
+
+# --- filter keeping only the bbb client -------------------------------------
+$TMUX choose-client -t aaa:0 -F 'C2=#{client_session}' \
+	-f '#{==:#{client_session},bbb}' || exit 1
+wait_for 'C2='
+out=$(capture)
+echo "$out" | grep -q 'C2=bbb' || fail "bbb client missing when it matches"
+echo "$out" | grep -q 'C2=aaa' && fail "aaa client shown but does not match"
+[ "$(echo "$out" | grep -c 'C2=')" -eq 1 ] || fail "expected 1 client"
+$TMUX send-keys -t aaa:0 q
+
+# --- no filter shows both clients -------------------------------------------
+$TMUX choose-client -t aaa:0 -F 'C3=#{client_session}' || exit 1
+wait_for 'C3='
+out=$(capture)
+echo "$out" | grep -q 'C3=aaa' || fail "aaa client missing with no filter"
+echo "$out" | grep -q 'C3=bbb' || fail "bbb client missing with no filter"
+[ "$(echo "$out" | grep -c 'C3=')" -eq 2 ] || fail "expected 2 clients"
+$TMUX send-keys -t aaa:0 q
+
+# --- filter matching nothing ------------------------------------------------
+#
+# Everything is shown and the filter indicator reports no matches.
+$TMUX choose-client -t aaa:0 -F 'C4=#{client_session}' \
+	-f '#{==:#{client_session},nosuch}' || exit 1
+wait_for 'C4='
+out=$(capture)
+echo "$out" | grep -q 'C4=aaa' || fail "aaa client missing with no-match filter"
+echo "$out" | grep -q 'C4=bbb' || fail "bbb client missing with no-match filter"
+echo "$out" | grep -q 'no matches' || fail "no matches indicator missing"
+$TMUX send-keys -t aaa:0 q
+
+# --- Enter runs the default command (detach-client) --------------------------
+#
+# The filter leaves only the bbb client listed and selected; Enter detaches
+# it, leaving only the aaa client attached.
+$TMUX choose-client -t aaa:0 -F 'G1=#{client_session}' \
+	-f '#{==:#{client_session},bbb}' || exit 1
+wait_for 'G1=bbb'
+$TMUX send-keys -t aaa:0 Enter
+wait_clients 1 || fail "bbb client did not detach"
+[ "$($TMUX list-clients -F '#{client_session}')" = "aaa" ] || \
+	fail "wrong client detached"
+
+cleanup
+exit 0
diff --git a/regress/choose-tree.sh b/regress/choose-tree.sh
new file mode 100644
index 000000000..a82e42c20
--- /dev/null
+++ b/regress/choose-tree.sh
@@ -0,0 +1,247 @@
+#!/bin/sh
+
+# Tests of tree mode (window-tree.c) as driven by choose-tree.
+#
+# Filtering: the -f filter is applied per pane and removes panes, windows and
+# sessions with no matching panes (a window with more than one pane and no
+# matching panes must disappear - GitHub issue 5326); -h keeps a window
+# listed when its only matching pane is the pane the tree is drawn in; a
+# filter matching nothing falls back to showing everything.
+#
+# Sorting: -O and -r change the sort order.
+#
+# Keys: h and l collapse and expand; f prompts for a filter and c clears it;
+# g goes to the top; Enter runs the default command (switch-client); x kills
+# the current item after a confirmation prompt.
+#
+# The tree is drawn on a mode screen which capture-pane does not show, so - as
+# in environ-update.sh - a second server provides a client: an inner "tmux
+# attach" runs inside a pane of the second server, and that pane is captured
+# to read what the inner client rendered. Each choose-tree call uses a
+# distinct -F marker so a capture can be tied to the call it belongs to.
+
+PATH=/bin:/usr/bin
+TERM=screen
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+TMUX="$TEST_TMUX -Ltest -f/dev/null"
+TMUX2="$TEST_TMUX -Ltest2 -f/dev/null"
+
+cleanup()
+{
+	$TMUX kill-server 2>/dev/null
+	$TMUX2 kill-server 2>/dev/null
+}
+fail()
+{
+	echo "$1"
+	cleanup
+	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 $marker, so the
+# capture is known to show the mode instance under test.
+wait_for()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		if capture | grep -q "$1"; then
+			sleep 0.2
+			return 0
+		fi
+		sleep 0.2
+		i=$((i + 1))
+	done
+	fail "timed out waiting for '$1'"
+}
+
+# wait_count $marker $n
+#
+# Wait (up to ~10s) until exactly $n rendered lines contain $marker.
+wait_count()
+{
+	i=0
+	while [ "$i" -lt 50 ]; do
+		[ "$(capture | grep -c "$1")" -eq "$2" ] && return 0
+		sleep 0.2
+		i=$((i + 1))
+	done
+	fail "timed out waiting for $2 lines of '$1' (have $(capture | grep -c "$1"))"
+}
+
+# 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
+}
+
+$TMUX kill-server 2>/dev/null
+$TMUX2 kill-server 2>/dev/null
+
+# Session zzz is created first, so it sorts first by index, and has a
+# two-pane window 0 and a single-pane window 1. Session aaa has one window
+# with one pane and is where the tree is displayed. With everything expanded
+# and no filter the tree is nine lines:
+#
+#	0 zzz  1 window 0  2 pane 0  3 pane 1  4 window 1  5 pane 0
+#	6 aaa  7 window 0  8 pane 0
+$TMUX new-session -d -s zzz -x 80 -y 24 || exit 1
+$TMUX split-window -t zzz:0 || exit 1
+$TMUX new-window -t zzz || exit 1
+$TMUX new-session -d -s aaa -x 80 -y 24 || 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"
+
+# --- filter keeping only aaa ------------------------------------------------
+#
+# zzz must disappear entirely: its single-pane window 1 and - the GitHub 5326
+# regression - its two-pane window 0. aaa contributes exactly three lines
+# (session, window, pane).
+$TMUX choose-tree -t aaa:0 -F 'F1' -f '#{==:#{session_name},aaa}' || exit 1
+wait_count 'F1' 3
+out=$(capture)
+echo "$out" | grep -q 'aaa: F1' || fail "aaa missing when filter matches it"
+echo "$out" | grep -q 'zzz: F1' && fail "zzz shown but no pane matches"
+$TMUX send-keys -t aaa:0 q
+
+# --- filter keeping only zzz ------------------------------------------------
+#
+# zzz contributes six lines (session, two windows, three panes); aaa must
+# disappear.
+$TMUX choose-tree -t aaa:0 -F 'F2' -f '#{==:#{session_name},zzz}' || exit 1
+wait_count 'F2' 6
+out=$(capture)
+echo "$out" | grep -q 'zzz: F2' || fail "zzz missing when filter matches it"
+echo "$out" | grep -q 'aaa: F2' && fail "aaa shown but no pane matches"
+$TMUX send-keys -t aaa:0 q
+
+# --- filter matching a single pane ------------------------------------------
+#
+# Only pane 1 of zzz:0 matches, so the tree is exactly session zzz, window 0
+# and that pane; zzz:1 and all of aaa must disappear.
+$TMUX choose-tree -t aaa:0 -F 'F3' -f '#{==:#{pane_index},1}' || exit 1
+wait_count 'F3' 3
+out=$(capture)
+echo "$out" | grep -q 'zzz: F3' || fail "zzz missing when its pane matches"
+echo "$out" | grep -q 'aaa: F3' && fail "aaa shown but no pane matches"
+echo "$out" | grep -q '1: F3' || fail "matching pane missing"
+$TMUX send-keys -t aaa:0 q
+
+# --- filter matching nothing ------------------------------------------------
+#
+# Everything is shown and the filter indicator reports no matches.
+$TMUX choose-tree -t aaa:0 -F 'F4' -f '#{==:#{session_name},nosuch}' || exit 1
+wait_for 'F4'
+out=$(capture)
+echo "$out" | grep -q 'aaa: F4' || fail "aaa missing with no-match filter"
+echo "$out" | grep -q 'zzz: F4' || fail "zzz missing with no-match filter"
+echo "$out" | grep -q 'no matches' || fail "no matches indicator missing"
+$TMUX send-keys -t aaa:0 q
+
+# --- -h with the tree pane as the only match --------------------------------
+#
+# With -h the pane the tree is drawn in is hidden, but it still counts as a
+# match, so session and window aaa stay listed: two lines, no pane line.
+$TMUX choose-tree -h -t aaa:0 -F 'F5' -f '#{==:#{session_name},aaa}' || \
+	exit 1
+wait_count 'F5' 2
+capture | grep -q 'aaa: F5' || fail "aaa missing with -h"
+$TMUX send-keys -t aaa:0 q
+
+# --- sort orders ------------------------------------------------------------
+#
+# By index zzz (created first) sorts first, by name aaa does, and -r reverses.
+$TMUX choose-tree -t aaa:0 -F 'F6' -O index || exit 1
+wait_for 'F6'
+capture | grep 'F6' | head -1 | grep -q 'zzz: F6' || \
+	fail "zzz not first with -O index"
+$TMUX send-keys -t aaa:0 q
+
+$TMUX choose-tree -t aaa:0 -F 'F7' -O name || exit 1
+wait_for 'F7'
+capture | grep 'F7' | head -1 | grep -q 'aaa: F7' || \
+	fail "aaa not first with -O name"
+$TMUX send-keys -t aaa:0 q
+
+$TMUX choose-tree -t aaa:0 -F 'F8' -O name -r || exit 1
+wait_for 'F8'
+capture | grep 'F8' | head -1 | grep -q 'zzz: F8' || \
+	fail "zzz not first with -O name -r"
+$TMUX send-keys -t aaa:0 q
+
+# --- collapse and expand with h and l -----------------------------------------
+#
+# g moves to the top (session zzz); h collapses it, hiding its five children;
+# l expands it again.
+$TMUX choose-tree -t aaa:0 -F 'G1' -O index || exit 1
+wait_count 'G1' 9
+$TMUX send-keys -t aaa:0 g h
+wait_count 'G1' 4
+$TMUX send-keys -t aaa:0 l
+wait_count 'G1' 9
+$TMUX send-keys -t aaa:0 q
+
+# --- filter entered at the prompt with f, cleared with c ----------------------
+$TMUX choose-tree -t aaa:0 -F 'G2' -O index || exit 1
+wait_count 'G2' 9
+$TMUX send-keys -t aaa:0 f
+$TMUX send-keys -t aaa:0 -l '#{==:#{session_name},aaa}'
+$TMUX send-keys -t aaa:0 Enter
+wait_count 'G2' 3
+out=$(capture)
+echo "$out" | grep -q 'aaa: G2' || fail "aaa missing with prompt filter"
+echo "$out" | grep -q 'zzz: G2' && fail "zzz shown with prompt filter"
+$TMUX send-keys -t aaa:0 c
+wait_count 'G2' 9
+$TMUX send-keys -t aaa:0 q
+
+# --- Enter runs the default command (switch-client) ----------------------------
+#
+# g selects session zzz and Enter switches the client to it.
+$TMUX choose-tree -t aaa:0 -F 'G3' -O index || exit 1
+wait_count 'G3' 9
+$TMUX send-keys -t aaa:0 g Enter
+i=0
+while [ "$i" -lt 50 ]; do
+	[ "$($TMUX list-clients -F '#{client_session}')" = "zzz" ] && break
+	sleep 0.2
+	i=$((i + 1))
+done
+[ "$i" -lt 50 ] || fail "client did not switch to zzz"
+$TMUX switch-client -c "$($TMUX list-clients -F '#{client_name}')" -t aaa || \
+	exit 1
+
+# --- x kills the current item after confirmation -------------------------------
+#
+# g and four times j select window 1 of zzz; x asks for confirmation and y
+# kills it, leaving zzz with one window and the tree with seven lines.
+$TMUX choose-tree -t aaa:0 -F 'G4' -O index || exit 1
+wait_count 'G4' 9
+$TMUX send-keys -t aaa:0 g j j j j x
+wait_for 'Kill window 1'
+$TMUX send-keys -t aaa:0 y
+wait_count 'G4' 7
+[ "$($TMUX list-windows -t zzz -F x | grep -c x)" -eq 1 ] || \
+	fail "window 1 of zzz not killed"
+$TMUX send-keys -t aaa:0 q
+
+cleanup
+exit 0