Do not raise a pane when the mouse moves onto it.

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

regress/mouse-raise.sh

@@ -0,0 +1,70 @@
+#!/bin/sh
+
+# Moving the mouse onto a pane with focus-follows-mouse makes it active without
+# raising it.
+
+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
+}
+
+# check PANE FORMAT EXPECTED
+check()
+{
+	got=$($TMUX display-message -p -t "$1" "$2")
+	[ "$got" = "$3" ] || fail "$1 $2: got '$got', expected '$3'"
+}
+
+# mouse SEQUENCE: send the escape sequence to the inner client.
+mouse()
+{
+	$TMUX2 send-keys -t "$OUTER" -l "$(printf "$1")" || fail "send-keys failed"
+	sleep 1
+}
+
+cleanup
+
+$TMUX new-session -d -s inner -x 80 -y 24 'sleep 100' || exit 1
+$TMUX set -g status off || exit 1
+$TMUX set -g mouse on || exit 1
+$TMUX set -g focus-follows-mouse on || exit 1
+$TMUX set -g pane-border-status top || exit 1
+A=$($TMUX display-message -p '#{pane_id}') || exit 1
+X=$($TMUX new-pane -dPF '#{pane_id}' -x 20 -y 6 -X 5 -Y 8 'sleep 100') || exit 1
+Y=$($TMUX new-pane -dPF '#{pane_id}' -x 20 -y 6 -X 45 -Y 8 'sleep 100') || 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 "$OUTER" ] || fail "No outer pane."
+
+# Moving onto a floating pane that is behind another one focuses it but does not
+# raise it, whatever pane-raise-on-focus says.
+check "$A" '#{pane_active}' 1
+check "$Y" '#{pane_z}' 0
+mouse '\033[<35;12;12M\033[<35;14;13M'
+check "$X" '#{pane_active}' 1
+check "$Y" '#{pane_z}' 0
+
+# Clicking inside a pane still raises a floating pane, as before.
+mouse '\033[<0;54;12M\033[<0;54;12m'
+check "$Y" '#{pane_active}:#{pane_z}' '1:0'
+mouse '\033[<0;14;12M\033[<0;14;12m'
+check "$X" '#{pane_active}:#{pane_z}' '1:0'
+
+cleanup
+exit 0