Add tests for zoomed and floating panes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

regress/border-zoom-click.sh

@@ -0,0 +1,51 @@
+#!/bin/sh
+
+# The zoom button on a pane's border must zoom the pane that was clicked, not
+# the active pane.
+
+PATH=/bin:/usr/bin
+TERM=screen
+
+[ -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
+}
+
+cleanup
+
+$TMUX new-session -d -s inner -x 80 -y 24 'sleep 100' || exit 1
+$TMUX set -g mouse on || exit 1
+$TMUX set -g pane-border-status top || exit 1
+$TMUX split-window -d -h 'sleep 100' || exit 1
+active=$($TMUX display-message -p '#{pane_id}') || exit 1
+other=$($TMUX list-panes -F '#{pane_id}' | grep -v "^$active\$") || exit 1
+
+$TMUX2 new-session -d -x 80 -y 24 "$TMUX attach -t inner" || exit 1
+sleep 1
+OUTER=$($TMUX2 list-panes -F '#{pane_id}' | head -1)
+[ -n "$OUTER" ] || fail "No outer pane."
+
+# The right hand pane's border ends with the buttons [f][z][x]; the zoom one is
+# the middle button, at column 76 (1-based) on the first row.
+seq=$(printf '\033[<0;76;1M\033[<0;76;1m')
+$TMUX2 send-keys -t "$OUTER" -l "$seq" || fail "send-keys failed."
+sleep 1
+
+got=$($TMUX display-message -p -t "$other" '#{pane_zoomed_flag}')
+[ "$got" = "1" ] || fail "clicked pane zoomed flag '$got', expected '1'"
+got=$($TMUX display-message -p -t "$active" '#{pane_zoomed_flag}')
+[ "$got" = "0" ] || fail "active pane zoomed flag '$got', expected '0'"
+
+cleanup
+exit 0