Add support for local windows for a client.

Makefile.am

@@ -85,6 +85,7 @@ endif
 
 # List of sources.
 dist_tmux_SOURCES = \
+	active.c \
 	alerts.c \
 	arguments.c \
 	attributes.c \

active.c

@@ -0,0 +1,449 @@
+/* $OpenBSD$ */
+
+/*
+ * Copyright (c) 2026 Nicholas Marriott <nicholas.marriott@gmail.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 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.
+ */
+
+#include <sys/types.h>
+
+#include <stdlib.h>
+
+#include "tmux.h"
+
+/* Local last-window stack entry. */
+struct active_window_entry {
+	u_int					window;
+	TAILQ_ENTRY(active_window_entry)	entry;
+};
+
+/* Local last-window stack. */
+TAILQ_HEAD(active_window_stack, active_window_entry);
+
+/* Per-client and per-session local active window state. */
+struct active_window {
+	struct client			*client;
+	struct session			*session;
+
+	u_int				 window;
+	struct active_window_stack	 lastw;
+
+	RB_ENTRY(active_window)		 entry;
+};
+RB_HEAD(active_windows, active_window);
+
+static int
+active_window_cmp(struct active_window *aw1, struct active_window *aw2)
+{
+	uintptr_t	c1 = (uintptr_t)aw1->client;
+	uintptr_t	c2 = (uintptr_t)aw2->client;
+	uintptr_t	s1 = (uintptr_t)aw1->session;
+	uintptr_t	s2 = (uintptr_t)aw2->session;
+
+	if (c1 < c2)
+		return (-1);
+	if (c1 > c2)
+		return (1);
+	if (s1 < s2)
+		return (-1);
+	if (s1 > s2)
+		return (1);
+	return (0);
+}
+RB_GENERATE_STATIC(active_windows, active_window, entry, active_window_cmp);
+
+static struct active_window *active_get(struct client *, struct session *);
+static struct active_window *active_add(struct client *, struct session *,
+		    struct winlink *);
+static void	active_free(struct active_window *);
+static struct winlink *active_resolve(struct active_window *);
+static void	active_stack_remove(struct active_window_stack *, u_int);
+static void	active_stack_push(struct active_window_stack *, u_int);
+static void	active_changed(struct client *, struct session *,
+		    struct winlink *, struct winlink *);
+
+/* All local active window states. */
+static struct active_windows active_windows = RB_INITIALIZER(&active_windows);
+
+/* Find local active window state for a client and session. */
+static struct active_window *
+active_get(struct client *c, struct session *s)
+{
+	struct active_window	aw;
+
+	if (c == NULL || s == NULL)
+		return (NULL);
+	aw.client = c;
+	aw.session = s;
+	return (RB_FIND(active_windows, &active_windows, &aw));
+}
+
+/* Add local active window state for a client and session. */
+static struct active_window *
+active_add(struct client *c, struct session *s, struct winlink *wl)
+{
+	struct active_window	*aw;
+
+	aw = active_get(c, s);
+	if (aw == NULL) {
+		aw = xcalloc(1, sizeof *aw);
+		aw->client = c;
+		aw->session = s;
+		TAILQ_INIT(&aw->lastw);
+		RB_INSERT(active_windows, &active_windows, aw);
+	}
+	if (wl != NULL)
+		aw->window = wl->window->id;
+	return (aw);
+}
+
+/* Free local active window state. */
+static void
+active_free(struct active_window *aw)
+{
+	struct active_window_entry	*awe;
+
+	while (!TAILQ_EMPTY(&aw->lastw)) {
+		awe = TAILQ_FIRST(&aw->lastw);
+		TAILQ_REMOVE(&aw->lastw, awe, entry);
+		free(awe);
+	}
+	RB_REMOVE(active_windows, &active_windows, aw);
+	free(aw);
+}
+
+/* Resolve local active window state to a valid winlink. */
+static struct winlink *
+active_resolve(struct active_window *aw)
+{
+	struct winlink	*wl, *next;
+	u_int		 window;
+
+	if (aw == NULL || aw->session->curw == NULL)
+		return (NULL);
+
+	wl = winlink_find_by_window_id(&aw->session->windows, aw->window);
+	if (wl != NULL)
+		return (wl);
+
+	while (!TAILQ_EMPTY(&aw->lastw)) {
+		window = TAILQ_FIRST(&aw->lastw)->window;
+
+		next = winlink_find_by_window_id(&aw->session->windows, window);
+		active_stack_remove(&aw->lastw, window);
+		if (next != NULL) {
+			aw->window = next->window->id;
+			return (next);
+		}
+	}
+
+	aw->window = aw->session->curw->window->id;
+	return (aw->session->curw);
+}
+
+/* Remove a window from a local last-window stack. */
+static void
+active_stack_remove(struct active_window_stack *stack, u_int window)
+{
+	struct active_window_entry	*awe, *awe1;
+
+	TAILQ_FOREACH_SAFE(awe, stack, entry, awe1) {
+		if (awe->window == window) {
+			TAILQ_REMOVE(stack, awe, entry);
+			free(awe);
+		}
+	}
+}
+
+/* Push a window onto a local last-window stack. */
+static void
+active_stack_push(struct active_window_stack *stack, u_int window)
+{
+	struct active_window_entry	*awe;
+
+	active_stack_remove(stack, window);
+	awe = xcalloc(1, sizeof *awe);
+	awe->window = window;
+	TAILQ_INSERT_HEAD(stack, awe, entry);
+}
+
+/* Notify the server that a client's effective window changed. */
+static void
+active_changed(struct client *c, struct session *s, struct winlink *wl,
+    struct winlink *old)
+{
+	struct event_payload	*ep;
+	struct cmd_find_state	 fs;
+
+	if (wl == NULL || wl == old)
+		return;
+
+	if (options_get_number(global_options, "focus-events")) {
+		if (old != NULL)
+			window_update_focus(old->window);
+		window_update_focus(wl->window);
+	}
+	winlink_clear_flags(wl);
+	window_update_activity(wl->window);
+	tty_update_window_offset(wl->window);
+
+	if (c != NULL && c->session == s)
+		wl->window->latest = c;
+
+	ep = event_payload_create();
+	cmd_find_from_winlink(&fs, wl, 0);
+	event_payload_set_target(ep, &fs);
+	event_payload_set_client(ep, "client", c);
+	event_payload_set_session(ep, "session", s);
+	event_payload_set_window(ep, "window", wl->window);
+	event_payload_set_window(ep, "new_window", wl->window);
+	event_payload_set_int(ep, "window_index", wl->idx);
+	event_payload_set_int(ep, "new_window_index", wl->idx);
+	if (old != NULL) {
+		event_payload_set_window(ep, "old_window", old->window);
+		event_payload_set_int(ep, "old_window_index", old->idx);
+	}
+	events_fire("client-window-changed", ep);
+
+	if (c != NULL) {
+		c->flags |= CLIENT_REDRAWWINDOW|CLIENT_REDRAWSTATUS|
+		    CLIENT_REDRAWBORDERS;
+		tty_update_client_offset(c);
+		status_update_cache(s);
+	}
+	recalculate_sizes();
+}
+
+/* Return if a client has local window selection for a session. */
+int
+active_is_local_window(struct client *c, struct session *s)
+{
+	return (active_get(c, s) != NULL);
+}
+
+/* Make a client use local or shared window selection for a session. */
+void
+active_set_local_window(struct client *c, struct session *s,
+    enum active_window_mode mode)
+{
+	struct active_window	*aw;
+	struct winlink		*wl, *old;
+
+	if (c == NULL || s == NULL || s->curw == NULL)
+		return;
+
+	old = active_get_effective_winlink(c, s);
+	if (mode == ACTIVE_LOCAL) {
+		active_add(c, s, old);
+		if (c != NULL && c->session == s)
+			c->flags |= CLIENT_REDRAWSTATUS;
+		return;
+	}
+
+	aw = active_get(c, s);
+	if (aw != NULL) {
+		active_free(aw);
+		wl = active_get_effective_winlink(c, s);
+		active_changed(c, s, wl, old);
+		if (c != NULL && c->session == s)
+			c->flags |= CLIENT_REDRAWSTATUS;
+	}
+}
+
+/* Return the effective winlink for a client and session. */
+struct winlink *
+active_get_effective_winlink(struct client *c, struct session *s)
+{
+	struct active_window	*aw;
+
+	if (s == NULL)
+		return (NULL);
+	aw = active_get(c, s);
+	if (aw != NULL)
+		return (active_resolve(aw));
+	return (s->curw);
+}
+
+/* Return the effective window for a client and session. */
+struct window *
+active_get_effective_window(struct client *c, struct session *s)
+{
+	struct winlink	*wl;
+
+	wl = active_get_effective_winlink(c, s);
+	if (wl == NULL)
+		return (NULL);
+	return (wl->window);
+}
+
+/* Select a winlink for a client and session. */
+int
+active_select_window(struct client *c, struct session *s, struct winlink *wl)
+{
+	struct active_window	*aw;
+	struct winlink		*old;
+	int			 changed;
+
+	if (wl == NULL)
+		return (-1);
+	aw = active_get(c, s);
+	if (aw == NULL)
+		return (session_set_current(s, wl));
+
+	old = active_resolve(aw);
+	if (old == wl)
+		return (1);
+	if (old != NULL)
+		active_stack_push(&aw->lastw, old->window->id);
+	active_stack_remove(&aw->lastw, wl->window->id);
+	aw->window = wl->window->id;
+	changed = (old != wl);
+	active_changed(c, s, wl, old);
+	return (changed ? 0 : 1);
+}
+
+/* Select a window by index. */
+int
+active_select_window_index(struct client *c, struct session *s, int idx)
+{
+	struct winlink	*wl;
+
+	wl = winlink_find_by_index(&s->windows, idx);
+	return (active_select_window(c, s, wl));
+}
+
+/* Select the next window. */
+int
+active_next_window(struct client *c, struct session *s, int alert)
+{
+	struct winlink	*wl;
+
+	wl = active_get_effective_winlink(c, s);
+	if (wl == NULL)
+		return (-1);
+	do {
+		wl = winlink_next(wl);
+		if (wl == NULL)
+			wl = RB_MIN(winlinks, &s->windows);
+		if (!alert || (wl->flags & WINLINK_ALERTFLAGS))
+			return (active_select_window(c, s, wl));
+	} while (wl != active_get_effective_winlink(c, s));
+	return (-1);
+}
+
+/* Select the previous window. */
+int
+active_previous_window(struct client *c, struct session *s, int alert)
+{
+	struct winlink	*wl;
+
+	wl = active_get_effective_winlink(c, s);
+	if (wl == NULL)
+		return (-1);
+	do {
+		wl = winlink_previous(wl);
+		if (wl == NULL)
+			wl = RB_MAX(winlinks, &s->windows);
+		if (!alert || (wl->flags & WINLINK_ALERTFLAGS))
+			return (active_select_window(c, s, wl));
+	} while (wl != active_get_effective_winlink(c, s));
+	return (-1);
+}
+
+/* Select the last window. */
+int
+active_last_window(struct client *c, struct session *s)
+{
+	struct active_window	*aw;
+	struct winlink		*wl;
+	u_int			 window;
+
+	aw = active_get(c, s);
+	if (aw == NULL)
+		return (session_last(s));
+	while (!TAILQ_EMPTY(&aw->lastw)) {
+		window = TAILQ_FIRST(&aw->lastw)->window;
+
+		wl = winlink_find_by_window_id(&s->windows, window);
+		if (wl != NULL)
+			return (active_select_window(c, s, wl));
+		active_stack_remove(&aw->lastw, window);
+	}
+	return (-1);
+}
+
+/* Remove all state for a client. */
+void
+active_remove_client(struct client *c)
+{
+	struct active_window	*aw, *aw1;
+
+	RB_FOREACH_SAFE(aw, active_windows, &active_windows, aw1) {
+		if (aw->client == c)
+			active_free(aw);
+	}
+}
+
+/* Remove all state for a session. */
+void
+active_remove_session(struct session *s)
+{
+	struct active_window	*aw, *aw1;
+
+	RB_FOREACH_SAFE(aw, active_windows, &active_windows, aw1) {
+		if (aw->session == s)
+			active_free(aw);
+	}
+}
+
+/* Remove a window from all local state. */
+void
+active_remove_window(struct window *w)
+{
+	struct active_window		*aw;
+
+	RB_FOREACH(aw, active_windows, &active_windows) {
+		active_stack_remove(&aw->lastw, w->id);
+		if (aw->window == w->id && aw->session->curw != NULL)
+			aw->window = aw->session->curw->window->id;
+	}
+}
+
+/* Return if this winlink is the effective winlink. */
+int
+active_is_effective_window(struct client *c, struct session *s,
+    struct winlink *wl)
+{
+	return (wl != NULL && wl == active_get_effective_winlink(c, s));
+}
+
+/* Return if this winlink is the last effective winlink. */
+int
+active_is_last_window(struct client *c, struct session *s, struct winlink *wl)
+{
+	struct active_window		*aw;
+	struct active_window_entry	*awe;
+
+	if (wl == NULL)
+		return (0);
+	aw = active_get(c, s);
+	if (aw == NULL)
+		return (wl == TAILQ_FIRST(&s->lastw));
+	TAILQ_FOREACH(awe, &aw->lastw, entry) {
+		if (winlink_find_by_window_id(&s->windows, awe->window) == NULL)
+			continue;
+		return (wl->window->id == awe->window);
+	}
+	return (0);
+}

alerts.c

@@ -314,7 +314,7 @@ alerts_set_message(struct winlink *wl, const char *type, const char *option)
 			tty_putcode(&c->tty, TTYC_BEL);
 		if (visual == VISUAL_OFF)
 			continue;
-		if (c->session->curw == wl) {
+		if (active_get_effective_winlink(c, c->session) == wl) {
 			status_message_set(c, -1, 1, 0, 0,
 			    "%s in current window", type);
 		} else {

cmd-attach-session.c

@@ -93,7 +93,7 @@ cmd_attach_session(struct cmdq_item *item, const char *tflag, int dflag,
 	if (wl != NULL) {
 		if (wp != NULL)
 			window_set_active_pane(wp->window, wp, 1);
-		session_set_current(s, wl);
+		active_select_window(c, s, wl);
 		if (wp != NULL)
 			cmd_find_from_winlink_pane(current, wl, wp, 0);
 		else

cmd-break-pane.c

@@ -93,14 +93,18 @@ cmd_break_pane_exec(struct cmd *self, struct cmdq_item *item)
 	struct cmd_find_state	*current = cmdq_get_current(item);
 	struct cmd_find_state	*target = cmdq_get_target(item);
 	struct cmd_find_state	*source = cmdq_get_source(item);
+	struct client		*c = cmdq_get_client(item);
 	struct client		*tc = cmdq_get_target_client(item);
+	struct client		*ac;
 	struct winlink		*wl = source->wl;
+	struct winlink		*current_wl;
 	struct session		*src_s = source->s;
 	struct session		*dst_s = target->s;
 	struct window_pane	*wp = source->wp;
 	struct window		*w = wl->window, *old_w = w;
 	char			*cause, *cp;
 	int			 idx = target->idx, before, old_idx = wl->idx;
+	int			 detached, local;
 	const char		*template, *name = args_get(args, 'n');
 
 	if (wp == w->modal) {
@@ -117,11 +121,18 @@ cmd_break_pane_exec(struct cmd *self, struct cmdq_item *item)
 	}
 
 	before = args_has(args, 'b');
+	ac = tc;
+	if (ac == NULL || ac->session != dst_s)
+		ac = c;
+	detached = args_has(args, 'd');
+	local = (!detached && active_is_local_window(ac, dst_s));
 	if (args_has(args, 'a') || before) {
 		if (target->wl != NULL)
 			idx = winlink_shuffle_up(dst_s, target->wl, before);
-		else
+		else {
-			idx = winlink_shuffle_up(dst_s, dst_s->curw, before);
+			current_wl = active_get_effective_winlink(ac, dst_s);
+			idx = winlink_shuffle_up(dst_s, current_wl, before);
+		}
 		if (idx == -1)
 			return (CMD_RETURN_ERROR);
 	}
@@ -129,7 +140,7 @@ cmd_break_pane_exec(struct cmd *self, struct cmdq_item *item)
 
 	if (window_count_panes(w, 1) == 1) {
 		if (server_link_window(src_s, wl, dst_s, idx, 0,
-		    !args_has(args, 'd'), &cause) != 0) {
+		    !detached && !local, &cause) != 0) {
 			cmdq_error(item, "%s", cause);
 			free(cause);
 			return (CMD_RETURN_ERROR);
@@ -142,6 +153,13 @@ cmd_break_pane_exec(struct cmd *self, struct cmdq_item *item)
 		wl = winlink_find_by_window(&dst_s->windows, w);
 		if (wl == NULL)
 			return (CMD_RETURN_ERROR);
+		if (local) {
+			active_select_window(ac, dst_s, wl);
+			if (ac != NULL && ac->session == dst_s)
+				cmd_find_from_client(current, ac, 0);
+			if (ac != NULL && ac->session == dst_s)
+				server_redraw_client(ac);
+		}
 		window_fire_pane_moved(wp, old_w, old_idx, w, wl->idx);
 		goto out;
 	}
@@ -183,9 +201,17 @@ cmd_break_pane_exec(struct cmd *self, struct cmdq_item *item)
 	window_remove_ref(w, __func__);
 	events_fire_window("window-created", w);
 	window_fire_pane_moved(wp, old_w, old_idx, w, wl->idx);
-	if (!args_has(args, 'd')) {
+	if (!detached) {
-		session_select(dst_s, wl->idx);
+		if (local)
-		cmd_find_from_session(current, dst_s, 0);
+			active_select_window(ac, dst_s, wl);
+		else
+			session_select(dst_s, wl->idx);
+		if (local && ac != NULL && ac->session == dst_s)
+			cmd_find_from_client(current, ac, 0);
+		else
+			cmd_find_from_session(current, dst_s, 0);
+		if (local && ac != NULL && ac->session == dst_s)
+			server_redraw_client(ac);
 	}
 
 	server_redraw_session(src_s);

cmd-display-menu.c

@@ -483,7 +483,7 @@ cmd_display_menu_exec(struct cmd *self, struct cmdq_item *item)
 	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;
+	struct options		*o = target->w->options;
 	struct options_entry	*oe;
 
 	if (args_has(args, 'C')) {
@@ -584,7 +584,7 @@ cmd_display_popup_exec(struct cmd *self, struct cmdq_item *item)
 	u_int			 px, py, w, h, count = args_count(args);
 	struct args_value	*av;
 	struct environ		*env = NULL;
-	struct options		*o = s->curw->window->options;
+	struct options		*o = target->w->options;
 	struct options_entry	*oe;
 
 	if (args_has(args, 'C')) {

cmd-find.c

@@ -884,13 +884,13 @@ cmd_find_from_client(struct cmd_find_state *fs, struct client *c, int flags)
 	if (c->session != NULL) {
 		cmd_find_clear_state(fs, flags);
 
-		fs->wp = c->session->curw->window->active;
+		fs->wl = active_get_effective_winlink(c, c->session);
+		fs->wp = fs->wl->window->active;
 		if (fs->wp == NULL) {
 			cmd_find_from_session(fs, c->session, flags);
 			return (0);
 		}
 		fs->s = c->session;
-		fs->wl = fs->s->curw;
 		fs->w = fs->wl->window;
 
 		cmd_find_log_state(__func__, fs);
@@ -931,6 +931,57 @@ unknown_pane:
 	return (cmd_find_from_nothing(fs, flags));
 }
 
+/* Find state from mouse target. */
+static int
+cmd_find_target_from_mouse(struct cmd_find_state *fs, struct cmdq_item *item,
+    enum cmd_find_type type)
+{
+	struct mouse_event	*m = &cmdq_get_event(item)->m;
+	struct client		*c = cmdq_get_client(item);
+	struct client		*tc = cmdq_get_target_client(item);
+
+	switch (type) {
+	case CMD_FIND_PANE:
+		if (m->s != -1 && m->w == -1 && m->wp == -1 &&
+		    (fs->s = session_find_by_id(m->s)) != NULL) {
+			if (tc != NULL && tc->session == fs->s)
+				fs->wl = active_get_effective_winlink(tc, fs->s);
+			else if (c != NULL && c->session == fs->s)
+				fs->wl = active_get_effective_winlink(c, fs->s);
+			else
+				fs->wl = fs->s->curw;
+			if (fs->wl != NULL) {
+				fs->w = fs->wl->window;
+				fs->wp = fs->w->active;
+				break;
+			}
+		}
+		fs->wp = cmd_mouse_pane(m, &fs->s, &fs->wl);
+		if (fs->wp != NULL) {
+			fs->w = fs->wl->window;
+			break;
+		}
+		/* FALLTHROUGH */
+	case CMD_FIND_WINDOW:
+	case CMD_FIND_SESSION:
+		fs->wl = cmd_mouse_window(m, &fs->s);
+		if (fs->s != NULL && m->w == -1 &&
+		    tc != NULL && tc->session == fs->s)
+			fs->wl = active_get_effective_winlink(tc, fs->s);
+		else if (fs->s != NULL && m->w == -1 &&
+		    c != NULL && c->session == fs->s)
+			fs->wl = active_get_effective_winlink(c, fs->s);
+		if (fs->wl == NULL && fs->s != NULL)
+			fs->wl = fs->s->curw;
+		if (fs->wl != NULL) {
+			fs->w = fs->wl->window;
+			fs->wp = fs->w->active;
+		}
+		break;
+	}
+	return (fs->wp == NULL ? -1 : 0);
+}
+
 /*
  * Split target into pieces and resolve for the given type. Fills in the given
  * state. Returns 0 on success or -1 on error.
@@ -939,7 +990,6 @@ int
 cmd_find_target(struct cmd_find_state *fs, struct cmdq_item *item,
     const char *target, enum cmd_find_type type, int flags)
 {
-	struct mouse_event	*m;
 	struct client		*c;
 	struct cmd_find_state	 current;
 	char			*colon, *period, *copy = NULL, tmp[256];
@@ -1015,35 +1065,15 @@ cmd_find_target(struct cmd_find_state *fs, struct cmdq_item *item,
 			cmdq_error(item, "no current client");
 			goto error;
 		}
-		fs->wl = c->session->curw;
+		fs->wl = active_get_effective_winlink(c, c->session);
-		fs->wp = c->session->curw->window->active;
+		fs->wp = fs->wl->window->active;
-		fs->w = c->session->curw->window;
+		fs->w = fs->wl->window;
 		goto found;
 	}
 
 	/* Mouse target is a plain = or {mouse}. */
 	if (strcmp(target, "=") == 0 || strcmp(target, "{mouse}") == 0) {
-		m = &cmdq_get_event(item)->m;
+		if (cmd_find_target_from_mouse(fs, item, type) != 0) {
-		switch (type) {
-		case CMD_FIND_PANE:
-			fs->wp = cmd_mouse_pane(m, &fs->s, &fs->wl);
-			if (fs->wp != NULL) {
-				fs->w = fs->wl->window;
-				break;
-			}
-			/* FALLTHROUGH */
-		case CMD_FIND_WINDOW:
-		case CMD_FIND_SESSION:
-			fs->wl = cmd_mouse_window(m, &fs->s);
-			if (fs->wl == NULL && fs->s != NULL)
-				fs->wl = fs->s->curw;
-			if (fs->wl != NULL) {
-				fs->w = fs->wl->window;
-				fs->wp = fs->w->active;
-			}
-			break;
-		}
-		if (fs->wp == NULL) {
 			if (~flags & CMD_FIND_QUIET)
 				cmdq_error(item, "no mouse target");
 			goto error;

cmd-join-pane.c

@@ -410,13 +410,16 @@ cmd_join_pane_exec(struct cmd *self, struct cmdq_item *item)
 	struct cmd_find_state	*current = cmdq_get_current(item);
 	struct cmd_find_state	*target = cmdq_get_target(item);
 	struct cmd_find_state	*source = cmdq_get_source(item);
+	struct client		*c = cmdq_get_client(item);
+	struct client		*tc = cmdq_get_target_client(item);
+	struct client		*ac;
 	struct session		*dst_s;
 	struct winlink		*src_wl, *dst_wl;
 	struct window		*src_w, *dst_w;
 	struct window_pane	*src_wp, *dst_wp;
 	const char		*s;
 	char			*cause = NULL;
-	int			 flags = 0, dst_idx;
+	int			 flags = 0, dst_idx, local;
 	struct layout_cell	*lc;
 
 	dst_s = target->s;
@@ -424,6 +427,10 @@ cmd_join_pane_exec(struct cmd *self, struct cmdq_item *item)
 	dst_wp = target->wp;
 	dst_w = dst_wl->window;
 	dst_idx = dst_wl->idx;
+	ac = tc;
+	if (ac == NULL || ac->session != dst_s)
+		ac = c;
+	local = active_is_local_window(ac, dst_s);
 
 	if (cmd_get_entry(self) == &cmd_move_pane_entry) {
 		if (args_has(args, 'M'))
@@ -511,9 +518,18 @@ cmd_join_pane_exec(struct cmd *self, struct cmdq_item *item)
 
 	if (!args_has(args, 'd')) {
 		window_set_active_pane(dst_w, src_wp, 1);
-		session_select(dst_s, dst_idx);
+		if (local)
-		cmd_find_from_session(current, dst_s, 0);
+			active_select_window(ac, dst_s, dst_wl);
-		server_redraw_session(dst_s);
+		else
+			session_select(dst_s, dst_idx);
+		if (local && ac != NULL && ac->session == dst_s)
+			cmd_find_from_client(current, ac, 0);
+		else
+			cmd_find_from_session(current, dst_s, 0);
+		if (local && ac != NULL && ac->session == dst_s)
+			server_redraw_client(ac);
+		else
+			server_redraw_session(dst_s);
 	} else
 		server_status_session(dst_s);
 

cmd-move-window.c

@@ -62,12 +62,15 @@ cmd_move_window_exec(struct cmd *self, struct cmdq_item *item)
 	struct args		*args = cmd_get_args(self);
 	struct cmd_find_state	*source = cmdq_get_source(item);
 	struct cmd_find_state	 target;
+	struct client		*c = cmdq_get_client(item);
+	struct client		*tc = cmdq_get_target_client(item);
+	struct client		*ac;
 	const char		*tflag = args_get(args, 't');
 	struct session		*src = source->s;
 	struct session		*dst;
-	struct winlink		*wl = source->wl;
+	struct winlink		*wl = source->wl, *dstwl, *current_wl;
 	char			*cause;
-	int			 idx, kflag, dflag, sflag, before;
+	int			 idx, kflag, dflag, sflag, before, local;
 
 	if (args_has(args, 'r')) {
 		if (cmd_find_target(&target, item, tflag, CMD_FIND_SESSION,
@@ -90,23 +93,37 @@ cmd_move_window_exec(struct cmd *self, struct cmdq_item *item)
 	dflag = args_has(args, 'd');
 	sflag = args_has(args, 's');
 
+	ac = tc;
+	if (ac == NULL || ac->session != dst)
+		ac = c;
+	local = (!dflag && active_is_local_window(ac, dst));
+
 	before = args_has(args, 'b');
 	if (args_has(args, 'a') || before) {
 		if (target.wl != NULL)
 			idx = winlink_shuffle_up(dst, target.wl, before);
-		else
+		else {
-			idx = winlink_shuffle_up(dst, dst->curw, before);
+			current_wl = active_get_effective_winlink(ac, dst);
+			idx = winlink_shuffle_up(dst, current_wl, before);
+		}
 		if (idx == -1)
 			return (CMD_RETURN_ERROR);
 	}
 
-	if (server_link_window(src, wl, dst, idx, kflag, !dflag, &cause) != 0) {
+	if (server_link_window(src, wl, dst, idx, kflag, !dflag && !local,
+	    &cause) != 0) {
 		cmdq_error(item, "%s", cause);
 		free(cause);
 		return (CMD_RETURN_ERROR);
 	}
+	dstwl = winlink_find_by_window(&dst->windows, wl->window);
 	if (cmd_get_entry(self) == &cmd_move_window_entry)
 		server_unlink_window(src, wl);
+	if (local && dstwl != NULL) {
+		active_select_window(ac, dst, dstwl);
+		if (ac != NULL && ac->session == dst)
+			server_redraw_client(ac);
+	}
 
 	/*
 	 * Renumber the winlinks in the src session only, the destination

cmd-new-window.c

@@ -58,9 +58,11 @@ cmd_new_window_exec(struct cmd *self, struct cmdq_item *item)
 	struct cmd_find_state	*target = cmdq_get_target(item);
 	struct spawn_context	 sc = { 0 };
 	struct client		*tc = cmdq_get_target_client(item);
+	struct client		*ac;
 	struct session		*s = target->s;
 	struct winlink		*wl = target->wl, *new_wl = NULL;
 	int			 idx = target->idx, before, count = args_count(args);
+	int			 detached, local;
 	char			*cause = NULL, *cp, *expanded, *wname = NULL;
 	const char		*template, *name;
 	struct cmd_find_state	 fs;
@@ -107,10 +109,15 @@ cmd_new_window_exec(struct cmd *self, struct cmdq_item *item)
 			free(wname);
 			if (args_has(args, 'd'))
 				return (CMD_RETURN_NORMAL);
-			if (session_set_current(s, new_wl) == 0)
+			if (active_select_window(c, s, new_wl) == 0) {
-				server_redraw_session(s);
+				if (active_is_local_window(c, s) && c != NULL &&
+				    c->session == s)
+					server_redraw_client(c);
+				else
+					server_redraw_session(s);
+			}
 			if (c != NULL && c->session != NULL)
-				s->curw->window->latest = c;
+				active_get_effective_window(c, s)->latest = c;
 			recalculate_sizes();
 			return (CMD_RETURN_NORMAL);
 		}
@@ -140,10 +147,16 @@ cmd_new_window_exec(struct cmd *self, struct cmdq_item *item)
 	sc.idx = idx;
 	sc.cwd = args_get(args, 'c');
 
+	ac = tc;
+	if (ac == NULL || ac->session != s)
+		ac = c;
+	detached = args_has(args, 'd');
+	local = (!detached && active_is_local_window(ac, s));
+
 	sc.flags = 0;
 	if (args_has(args, 'E') || (count == 1 && *args_string(args, 0) == '\0'))
 		sc.flags |= SPAWN_EMPTY;
-	if (args_has(args, 'd'))
+	if (detached || local)
 		sc.flags |= SPAWN_DETACHED;
 	if (args_has(args, 'k'))
 		sc.flags |= SPAWN_KILL;
@@ -153,7 +166,13 @@ cmd_new_window_exec(struct cmd *self, struct cmdq_item *item)
 		free(cause);
 		goto fail;
 	}
-	if (!args_has(args, 'd') || new_wl == s->curw) {
+	if (local) {
+		if (active_select_window(ac, s, new_wl) == 0)
+			cmd_find_from_winlink(current, new_wl, 0);
+		if (ac != NULL && ac->session == s)
+			server_redraw_client(ac);
+		server_status_session_group(s);
+	} else if (!detached || new_wl == s->curw) {
 		cmd_find_from_winlink(current, new_wl, 0);
 		server_redraw_session_group(s);
 	} else

cmd-refresh-client.c

@@ -203,7 +203,7 @@ cmd_refresh_client_exec(struct cmd *self, struct cmdq_item *item)
 		if (args_has(args, 'c'))
 			tc->pan_window = NULL;
 		else {
-			w = tc->session->curw->window;
+			w = active_get_effective_window(tc, tc->session);
 			if (tc->pan_window != w) {
 				tc->pan_window = w;
 				tc->pan_ox = tty->oox;

cmd-run-shell.c

@@ -79,7 +79,10 @@ static void
 cmd_run_shell_print(struct job *job, const char *msg)
 {
 	struct cmd_run_shell_data	*cdata = job_get_data(job);
+	struct client			*c;
+	struct session			*s;
 	struct window_pane		*wp = NULL;
+	struct window			*w;
 	struct cmd_find_state		 fs;
 	struct window_mode_entry	*wme;
 
@@ -90,8 +93,12 @@ cmd_run_shell_print(struct job *job, const char *msg)
 			cmdq_print(cdata->item, "%s", msg);
 			return;
 		}
-		if (cdata->client != NULL && cdata->client->session != NULL)
+		c = cdata->client;
-			wp = cdata->client->session->curw->window->active;
+		if (c != NULL && c->session != NULL) {
+			s = c->session;
+			w = active_get_effective_window(c, s);
+			wp = w->active;
+		}
 		if (wp == NULL && cmd_find_from_nothing(&fs, 0) == 0)
 			wp = fs.wp;
 		if (wp == NULL)

cmd-select-pane.c

@@ -68,10 +68,11 @@ cmd_select_pane_redraw(struct window *w)
 	TAILQ_FOREACH(c, &clients, entry) {
 		if (c->session == NULL || (c->flags & CLIENT_CONTROL))
 			continue;
-		if (c->session->curw->window == w && tty_window_bigger(&c->tty))
+		if (active_get_effective_window(c, c->session) == w &&
+		    tty_window_bigger(&c->tty))
 			server_redraw_client(c);
 		else {
-			if (c->session->curw->window == w)
+			if (active_get_effective_window(c, c->session) == w)
 				c->flags |= CLIENT_REDRAWBORDERS;
 			if (session_has(c->session, w))
 				c->flags |= CLIENT_REDRAWSTATUS;

cmd-select-window.c

@@ -33,8 +33,8 @@ const struct cmd_entry cmd_select_window_entry = {
 	.name = "select-window",
 	.alias = "selectw",
 
-	.args = { "lnpTt:", 0, 0, NULL },
+	.args = { "LlSnpTt:", 0, 0, NULL },
-	.usage = "[-lnpT] " CMD_TARGET_WINDOW_USAGE,
+	.usage = "[-LlnpST] " CMD_TARGET_WINDOW_USAGE,
 
 	.target = { 't', CMD_FIND_WINDOW, 0 },
 
@@ -88,8 +88,9 @@ cmd_select_window_exec(struct cmd *self, struct cmdq_item *item)
 	struct client		*c = cmdq_get_client(item);
 	struct cmd_find_state	*current = cmdq_get_current(item);
 	struct cmd_find_state	*target = cmdq_get_target(item);
-	struct winlink		*wl = target->wl;
+	struct winlink		*wl = target->wl, *current_wl;
 	struct session		*s = target->s;
+	enum active_window_mode	 mode;
 	int			 next, previous, last, activity;
 
 	next = (cmd_get_entry(self) == &cmd_next_window_entry);
@@ -102,48 +103,104 @@ cmd_select_window_exec(struct cmd *self, struct cmdq_item *item)
 	if (args_has(args, 'l'))
 		last = 1;
 
+	if (args_has(args, 'L') || args_has(args, 'S')) {
+		if (c == NULL || c->session == NULL) {
+			cmdq_error(item, "no current client");
+			return (CMD_RETURN_ERROR);
+		}
+		if (args_has(args, 'S'))
+			mode = ACTIVE_SHARED;
+		else
+			mode = ACTIVE_LOCAL;
+		active_set_local_window(c, s, mode);
+		if (!next &&
+		    !previous &&
+		    !last &&
+		    !args_has(args, 't') &&
+		    !args_has(args, 'T')) {
+			if (current->s == s) {
+				if (c->session == s)
+					cmd_find_from_client(current, c, 0);
+				else
+					cmd_find_from_session(current, s, 0);
+			}
+			if (c->session == s)
+				server_redraw_client(c);
+			else
+				server_redraw_session(s);
+			cmdq_insert_hook(s, item, current, "after-select-window");
+			recalculate_sizes();
+			return (CMD_RETURN_NORMAL);
+		}
+	}
+
+	if (active_is_local_window(c, s))
+		mode = ACTIVE_LOCAL;
+	else
+		mode = ACTIVE_SHARED;
 	if (next || previous || last) {
 		activity = args_has(args, 'a');
 		if (next) {
-			if (session_next(s, activity) != 0) {
+			if (active_next_window(c, s, activity) != 0) {
 				cmdq_error(item, "no next window");
 				return (CMD_RETURN_ERROR);
 			}
 		} else if (previous) {
-			if (session_previous(s, activity) != 0) {
+			if (active_previous_window(c, s, activity) != 0) {
 				cmdq_error(item, "no previous window");
 				return (CMD_RETURN_ERROR);
 			}
 		} else {
-			if (session_last(s) != 0) {
+			if (active_last_window(c, s) != 0) {
 				cmdq_error(item, "no last window");
 				return (CMD_RETURN_ERROR);
 			}
 		}
-		cmd_find_from_session(current, s, 0);
+		if (mode == ACTIVE_LOCAL && c != NULL && c->session == s)
-		server_redraw_session(s);
+			cmd_find_from_client(current, c, 0);
+		else
+			cmd_find_from_session(current, s, 0);
+		if (mode == ACTIVE_LOCAL && c != NULL && c->session == s)
+			server_redraw_client(c);
+		else
+			server_redraw_session(s);
 		cmdq_insert_hook(s, item, current, "after-select-window");
 	} else {
 		/*
 		 * If -T and select-window is invoked on same window as
 		 * current, switch to previous window.
 		 */
-		if (args_has(args, 'T') && wl == s->curw) {
+		current_wl = active_get_effective_winlink(c, s);
-			if (session_last(s) != 0) {
+		if (args_has(args, 'T') && wl == current_wl) {
+			if (active_last_window(c, s) != 0) {
 				cmdq_error(item, "no last window");
 				return (-1);
 			}
-			if (current->s == s)
+			if (current->s == s) {
+				if (mode == ACTIVE_LOCAL && c != NULL &&
+				    c->session == s)
+					cmd_find_from_client(current, c, 0);
+				else
+					cmd_find_from_session(current, s, 0);
+			}
+			if (mode == ACTIVE_LOCAL && c != NULL && c->session == s)
+				server_redraw_client(c);
+			else
+				server_redraw_session(s);
+		} else if (active_select_window(c, s, wl) == 0) {
+			if (mode == ACTIVE_LOCAL && c != NULL && c->session == s)
+				cmd_find_from_client(current, c, 0);
+			else
 				cmd_find_from_session(current, s, 0);
-			server_redraw_session(s);
+			if (mode == ACTIVE_LOCAL && c != NULL && c->session == s)
-		} else if (session_select(s, wl->idx) == 0) {
+				server_redraw_client(c);
-			cmd_find_from_session(current, s, 0);
+			else
-			server_redraw_session(s);
+				server_redraw_session(s);
 		}
 		cmdq_insert_hook(s, item, current, "after-select-window");
 	}
 	if (c != NULL && c->session != NULL)
-		s->curw->window->latest = c;
+		active_get_effective_window(c, s)->latest = c;
 	recalculate_sizes();
 
 	return (CMD_RETURN_NORMAL);

cmd-swap-window.c

@@ -48,10 +48,14 @@ cmd_swap_window_exec(struct cmd *self, struct cmdq_item *item)
 	struct args		*args = cmd_get_args(self);
 	struct cmd_find_state	*source = cmdq_get_source(item);
 	struct cmd_find_state	*target = cmdq_get_target(item);
+	struct client		*c = cmdq_get_client(item);
+	struct client		*tc = cmdq_get_target_client(item);
+	struct client		*ac;
 	struct session		*src = source->s, *dst = target->s;
 	struct session_group	*sg_src, *sg_dst;
 	struct winlink		*wl_src = source->wl, *wl_dst = target->wl;
 	struct window		*w_src, *w_dst;
+	int			 local_src, local_dst;
 
 	sg_src = session_group_contains(src);
 	sg_dst = session_group_contains(dst);
@@ -79,10 +83,22 @@ cmd_swap_window_exec(struct cmd *self, struct cmdq_item *item)
 
 	if (marked_pane.wl == wl_src)
 		marked_pane.wl = wl_dst;
+	ac = tc;
+	if (ac == NULL)
+		ac = c;
+	local_dst = active_is_local_window(ac, dst);
+	local_src = active_is_local_window(ac, src);
 	if (args_has(args, 'd')) {
-		session_select(dst, wl_dst->idx);
+		if (local_dst)
-		if (src != dst)
+			active_select_window(ac, dst, wl_dst);
-			session_select(src, wl_src->idx);
+		else
+			session_select(dst, wl_dst->idx);
+		if (src != dst) {
+			if (local_src)
+				active_select_window(ac, src, wl_src);
+			else
+				session_select(src, wl_src->idx);
+		}
 	}
 	session_group_synchronize_from(src);
 	server_redraw_session_group(src);

cmd-switch-client.c

@@ -53,11 +53,11 @@ cmd_switch_client_exec(struct cmd *self, struct cmdq_item *item)
 	struct cmd_find_state	 target;
 	const char		*tflag = args_get(args, 't');
 	enum cmd_find_type	 type;
-	int			 flags;
+	int			 flags, window_target;
 	struct client		*c = cmdq_get_client(item);
 	struct client		*tc = cmdq_get_target_client(item);
 	struct session		*s;
-	struct winlink		*wl;
+	struct winlink		*wl, *current_wl;
 	struct window		*w;
 	struct window_pane	*wp;
 	const char		*tablename;
@@ -65,8 +65,13 @@ cmd_switch_client_exec(struct cmd *self, struct cmdq_item *item)
 	struct sort_criteria	 sort_crit;
 	uid_t			 uid;
 
-	if (tflag != NULL &&
+	window_target = 0;
-	    (tflag[strcspn(tflag, ":.%")] != '\0' || strcmp(tflag, "=") == 0)) {
+	if (tflag != NULL) {
+		if (tflag[strcspn(tflag, ":.%")] != '\0' ||
+		    strcmp(tflag, "=") == 0)
+			window_target = 1;
+	}
+	if (window_target) {
 		type = CMD_FIND_PANE;
 		flags = 0;
 	} else {
@@ -137,7 +142,8 @@ cmd_switch_client_exec(struct cmd *self, struct cmdq_item *item)
 	} else {
 		if (cmdq_get_client(item) == NULL)
 			return (CMD_RETURN_NORMAL);
-		if (wl != NULL && wp != NULL && wp != wl->window->active) {
+		if (window_target && wl != NULL && wp != NULL &&
+		    wp != wl->window->active) {
 			w = wl->window;
 			if (window_push_zoom(w, 0, args_has(args, 'Z')))
 				server_redraw_window(w);
@@ -146,9 +152,13 @@ cmd_switch_client_exec(struct cmd *self, struct cmdq_item *item)
 			if (window_pop_zoom(w))
 				server_redraw_window(w);
 		}
-		if (wl != NULL) {
+		if (window_target && wl != NULL) {
-			session_set_current(s, wl);
+			active_select_window(tc, s, wl);
-			cmd_find_from_session(current, s, 0);
+			if (active_is_local_window(tc, s)) {
+				current_wl = active_get_effective_winlink(tc, s);
+				cmd_find_from_winlink(current, current_wl, 0);
+			} else
+				cmd_find_from_session(current, s, 0);
 		}
 	}
 

control-notify.c

@@ -215,6 +215,28 @@ control_client_session_changed_cb(__unused const char *name,
 	}
 }
 
+/* Notify control clients that a client changed its effective window. */
+static void
+control_client_window_changed_cb(__unused const char *name,
+    struct event_payload *ep, __unused void *sink_data)
+{
+	struct client		*cc = event_payload_get_client(ep, "client");
+	struct session		*s = event_payload_get_session(ep, "session");
+	struct window		*w = event_payload_get_window(ep, "window");
+	struct client		*c;
+
+	if (cc == NULL || s == NULL || w == NULL)
+		return;
+
+	TAILQ_FOREACH(c, &clients, entry) {
+		if (!CONTROL_SHOULD_NOTIFY_CLIENT(c))
+			continue;
+
+		control_write(c, "%%client-window-changed %s $%u @%u",
+		    cc->name, s->id, w->id);
+	}
+}
+
 /* Notify control clients that a client detached. */
 static void
 control_client_detached_cb(__unused const char *name, struct event_payload *ep,
@@ -356,6 +378,7 @@ control_build_events(void)
 		{ "window-linked", control_window_linked_cb },
 		{ "window-renamed", control_window_renamed_cb },
 		{ "client-session-changed", control_client_session_changed_cb },
+		{ "client-window-changed", control_client_window_changed_cb },
 		{ "client-detached", control_client_detached_cb },
 		{ "session-renamed", control_session_renamed_cb },
 		{ "session-created", control_session_created_cb },

format.c

@@ -800,7 +800,7 @@ format_cb_window_active_clients(struct format_tree *ft)
 		if (client_session == NULL)
 			continue;
 
-		if (w == client_session->curw->window)
+		if (w == active_get_effective_window(loop, client_session))
 			n++;
 	}
 
@@ -832,7 +832,7 @@ format_cb_window_active_clients_list(struct format_tree *ft)
 		if (client_session == NULL)
 			continue;
 
-		if (w == client_session->curw->window) {
+		if (w == active_get_effective_window(loop, client_session)) {
 			if (EVBUFFER_LENGTH(buffer) > 0)
 				evbuffer_add(buffer, ",", 1);
 			evbuffer_add_printf(buffer, "%s", loop->name);
@@ -2886,11 +2886,48 @@ format_cb_sixel_support(__unused struct format_tree *ft)
 static void *
 format_cb_active_window_index(struct format_tree *ft)
 {
-	if (ft->s != NULL)
+	struct winlink	*wl;
-		return (format_printf("%u", ft->s->curw->idx));
+
+	if (ft->s != NULL) {
+		wl = active_get_effective_winlink(ft->c, ft->s);
+		if (wl != NULL)
+			return (format_printf("%u", wl->idx));
+	}
 	return (NULL);
 }
 
+/* Callback for active_window_id. */
+static void *
+format_cb_active_window_id(struct format_tree *ft)
+{
+	struct winlink	*wl;
+
+	if (ft->s != NULL) {
+		wl = active_get_effective_winlink(ft->c, ft->s);
+		if (wl != NULL)
+			return (format_printf("@%u", wl->window->id));
+	}
+	return (NULL);
+}
+
+/* Callback for local_active_window. */
+static void *
+format_cb_local_active_window(struct format_tree *ft)
+{
+	if (ft->c != NULL && ft->s != NULL)
+		return (format_printf("%d", active_is_local_window(ft->c, ft->s)));
+	return (xstrdup("0"));
+}
+
+/* Callback for active_window_mode. */
+static void *
+format_cb_active_window_mode(struct format_tree *ft)
+{
+	if (ft->c != NULL && ft->s != NULL && active_is_local_window(ft->c, ft->s))
+		return (xstrdup("local"));
+	return (xstrdup("shared"));
+}
+
 /* Callback for last_window_index. */
 static void *
 format_cb_last_window_index(struct format_tree *ft)
@@ -2908,8 +2945,11 @@ format_cb_last_window_index(struct format_tree *ft)
 static void *
 format_cb_window_active(struct format_tree *ft)
 {
+	struct winlink	*wl;
+
 	if (ft->wl != NULL) {
-		if (ft->wl == ft->wl->session->curw)
+		wl = active_get_effective_winlink(ft->c, ft->wl->session);
+		if (ft->wl == wl)
 			return (xstrdup("1"));
 		return (xstrdup("0"));
 	}
@@ -2989,7 +3029,7 @@ static void *
 format_cb_window_flags(struct format_tree *ft)
 {
 	if (ft->wl != NULL)
-		return (xstrdup(window_printable_flags(ft->wl, 1)));
+		return (xstrdup(window_printable_flags(ft->c, ft->wl, 1)));
 	return (NULL);
 }
 
@@ -3176,7 +3216,7 @@ static void *
 format_cb_window_raw_flags(struct format_tree *ft)
 {
 	if (ft->wl != NULL)
-		return (xstrdup(window_printable_flags(ft->wl, 0)));
+		return (xstrdup(window_printable_flags(ft->c, ft->wl, 0)));
 	return (NULL);
 }
 
@@ -3386,9 +3426,15 @@ struct format_table_entry {
  * Only variables which are added by the caller go into the tree.
  */
 static const struct format_table_entry format_table[] = {
+	{ "active_window_id", FORMAT_TABLE_STRING,
+	  format_cb_active_window_id
+	},
 	{ "active_window_index", FORMAT_TABLE_STRING,
 	  format_cb_active_window_index
 	},
+	{ "active_window_mode", FORMAT_TABLE_STRING,
+	  format_cb_active_window_mode
+	},
 	{ "alternate_on", FORMAT_TABLE_STRING,
 	  format_cb_alternate_on
 	},
@@ -3557,6 +3603,9 @@ static const struct format_table_entry format_table[] = {
 	{ "last_window_index", FORMAT_TABLE_STRING,
 	  format_cb_last_window_index
 	},
+	{ "local_active_window", FORMAT_TABLE_STRING,
+	  format_cb_local_active_window
+	},
 	{ "mouse_all_flag", FORMAT_TABLE_STRING,
 	  format_cb_mouse_all_flag
 	},
@@ -5092,15 +5141,18 @@ format_add_window_neighbour(struct format_tree *nft, struct winlink *wl,
     struct session *s, const char *prefix)
 {
 	struct options_entry	*o;
+	struct winlink		*current;
 	const char		*oname;
 	char			*key, *prefixed, *oval;
 
+	current = active_get_effective_winlink(nft->c, s);
+
 	xasprintf(&key, "%s_window_index", prefix);
 	format_add(nft, key, "%u", wl->idx);
 	free(key);
 
 	xasprintf(&key, "%s_window_active", prefix);
-	format_add(nft, key, "%d", wl == s->curw);
+	format_add(nft, key, "%d", wl == current);
 	free(key);
 
 	o = options_first(wl->window->options);
@@ -5128,10 +5180,10 @@ format_loop_windows(struct format_expand_state *es, const char *fmt)
 	struct cmdq_item		*item = ft->item;
 	struct format_tree		*nft;
 	struct format_expand_state	 next;
-	char				*all, *active, *use, *expanded, *value;
+	char				*all, *active_fmt, *use, *expanded, *value;
 	struct evbuffer			*buffer;
 	size_t				 size;
-	struct winlink			*wl, **l;
+	struct winlink			*wl, **l, *active_wl;
 	struct window			*w;
 	int				 i, n;
 
@@ -5140,9 +5192,9 @@ format_loop_windows(struct format_expand_state *es, const char *fmt)
 		return (NULL);
 	}
 
-	if (format_choose(es, fmt, &all, &active, 0) != 0) {
+	if (format_choose(es, fmt, &all, &active_fmt, 0) != 0) {
 		all = xstrdup(fmt);
-		active = NULL;
+		active_fmt = NULL;
 	}
 
 	buffer = evbuffer_new();
@@ -5150,12 +5202,13 @@ format_loop_windows(struct format_expand_state *es, const char *fmt)
 		fatalx("out of memory");
 
 	l = sort_get_winlinks_session(s, &n, sc);
+	active_wl = active_get_effective_winlink(ft->c, s);
 	for (i = 0; i < n; i++) {
 		wl = l[i];
 		w = wl->window;
 		format_log(es, "window loop: %u @%u", wl->idx, w->id);
-		if (active != NULL && wl == s->curw)
+		if (active_fmt != NULL && wl == active_wl)
-			use = active;
+			use = active_fmt;
 		else
 			use = all;
 		nft = format_create(c, item, FORMAT_WINDOW|w->id, ft->flags);
@@ -5164,11 +5217,11 @@ format_loop_windows(struct format_expand_state *es, const char *fmt)
 		format_add(nft, "loop_last_flag", "%d", i == n - 1);
 
 		/* Add neighbour window data to the format tree. */
-		if (i > 0 && l[i - 1] == s->curw)
+		if (i > 0 && l[i - 1] == active_wl)
 			format_add(nft, "window_after_active", "1");
 		else
 			format_add(nft, "window_after_active", "0");
-		if (i + 1 < n && l[i + 1] == s->curw)
+		if (i + 1 < n && l[i + 1] == active_wl)
 			format_add(nft, "window_before_active", "1");
 		else
 			format_add(nft, "window_before_active", "0");
@@ -5188,7 +5241,7 @@ format_loop_windows(struct format_expand_state *es, const char *fmt)
 		free(expanded);
 	}
 
-	free(active);
+	free(active_fmt);
 	free(all);
 
 	if ((size = EVBUFFER_LENGTH(buffer)) != 0)
@@ -6691,7 +6744,7 @@ format_defaults(struct format_tree *ft, struct client *c, struct session *s,
 	if (s == NULL && c != NULL)
 		s = c->session;
 	if (wl == NULL && s != NULL)
-		wl = s->curw;
+		wl = active_get_effective_winlink(c, s);
 	if (wp == NULL && wl != NULL)
 		wp = wl->window->active;
 

key-bindings.c

@@ -31,6 +31,8 @@
 	" 'Rename' 'r' {command-prompt -I '#S' {rename-session -- '%%'}}" \
 	" 'Detach' 'd' {detach-client}" \
 	" ''" \
+	" '#{?local_active_window,Shared Window,Local Window}' 'L' {select-window #{?local_active_window,-S,-L}}" \
+	" ''" \
 	" 'New Session' 's' {new-session}" \
 	" 'New Window' 'w' {new-window}"
 #define DEFAULT_WINDOW_MENU \

menu.c

@@ -584,7 +584,7 @@ menu_display(struct menu *menu, int flags, int starting_choice,
 	struct options		*o;
 
 	if (fs == NULL)
-		w = c->session->curw->window;
+		w = active_get_effective_window(c, c->session);
 	else
 		w = fs->w;
 	o = w->options;

options-table.c

@@ -1115,7 +1115,8 @@ const struct options_table_entry options_table[] = {
 	{ .name = "status-style",
 	  .type = OPTIONS_TABLE_STRING,
 	  .scope = OPTIONS_TABLE_SESSION,
-	  .default_str = "bg=themegreen,fg=themeblack",
+	  .default_str = "bg=#{?local_active_window,themeblue,themegreen},"
+			 "fg=themeblack",
 	  .flags = OPTIONS_TABLE_IS_STYLE,
 	  .separator = ",",
 	  .text = "Style of the status line."
@@ -1960,6 +1961,8 @@ const struct options_table_entry options_table[] = {
 	    "Run when a client is resized."),
 	OPTIONS_TABLE_HOOK("client-session-changed", "",
 	    "Run when a client's attached session is changed."),
+	OPTIONS_TABLE_HOOK("client-window-changed", "",
+	    "Run when a client's effective window is changed."),
 	OPTIONS_TABLE_HOOK("client-light-theme", "",
 	    "Run when a client switches to a light theme."),
 	OPTIONS_TABLE_HOOK("client-dark-theme", "",

popup.c

@@ -102,9 +102,9 @@ popup_reapply_styles(struct popup_data *pd)
 
 	if (s == NULL)
 		return;
-	o = s->curw->window->options;
+	o = active_get_effective_window(c, s)->options;
 
-	ft = format_create_defaults(NULL, c, s, s->curw, NULL);
+	ft = format_create_defaults(NULL, c, s, NULL, NULL);
 
 	/* Reapply popup style from options. */
 	memcpy(&pd->defaults, &grid_default_cell, sizeof pd->defaults);
@@ -569,9 +569,9 @@ popup_display(int flags, enum box_lines lines, struct cmdq_item *item, u_int px,
 	struct style		 sytmp;
 
 	if (s != NULL)
-		o = s->curw->window->options;
+		o = active_get_effective_window(c, s)->options;
 	else
-		o = c->session->curw->window->options;
+		o = active_get_effective_window(c, c->session)->options;
 
 	if (lines == BOX_LINES_DEFAULT)
 		lines = options_get_number(o, "popup-border-lines");

regress/active-window.sh

@@ -0,0 +1,151 @@
+#!/bin/sh
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+LANG=C.UTF-8
+export TERM LC_ALL LANG
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+TMUX="$TEST_TMUX -LtestA$$ -f/dev/null"
+
+TMPDIR=$(mktemp -d)
+IN1="$TMPDIR/in1"
+IN2="$TMPDIR/in2"
+OUT1="$TMPDIR/out1"
+OUT2="$TMPDIR/out2"
+PID1=
+PID2=
+
+cleanup()
+{
+	[ -n "$PID1" ] && kill "$PID1" 2>/dev/null
+	[ -n "$PID2" ] && kill "$PID2" 2>/dev/null
+	$TMUX kill-server 2>/dev/null
+	rm -rf "$TMPDIR"
+}
+trap cleanup EXIT
+
+fail()
+{
+	echo "$1"
+	echo "client1:"
+	cat "$OUT1" 2>/dev/null
+	echo "client2:"
+	cat "$OUT2" 2>/dev/null
+	exit 1
+}
+
+wait_for()
+{
+	file=$1
+	pattern=$2
+	i=0
+
+	while [ "$i" -lt 60 ]; do
+		if grep -F -- "$pattern" "$file" >/dev/null 2>&1; then
+			return 0
+		fi
+		sleep 0.1
+		i=$((i + 1))
+	done
+	fail "missing '$pattern' in $file"
+}
+
+send1()
+{
+	printf '%s\n' "$*" >&3
+}
+
+send2()
+{
+	printf '%s\n' "$*" >&4
+}
+
+check_server()
+{
+	out=$($TMUX display-message -p -t "$1" "$2")
+	[ "$out" = "$3" ] || fail "expected '$3' for $1 $2, got '$out'"
+}
+
+$TMUX kill-server 2>/dev/null
+$TMUX new-session -d -s aw -x 80 -y 24 -n w0 || exit 1
+$TMUX new-window -d -t aw: -n w1 || exit 1
+$TMUX new-window -d -t aw: -n w2 || exit 1
+$TMUX new-session -d -s aw2 -x 80 -y 24 -n x0 || exit 1
+$TMUX new-window -d -t aw2: -n x1 || exit 1
+
+mkfifo "$IN1" "$IN2" || exit 1
+: >"$OUT1"
+: >"$OUT2"
+$TMUX -C attach-session -t aw <"$IN1" >"$OUT1" 2>&1 &
+PID1=$!
+$TMUX -C attach-session -t aw <"$IN2" >"$OUT2" 2>&1 &
+PID2=$!
+exec 3>"$IN1"
+exec 4>"$IN2"
+
+send1 'display-message -p C1READY'
+send2 'display-message -p C2READY'
+wait_for "$OUT1" C1READY
+wait_for "$OUT2" C2READY
+
+# Default shared selection: client 1 changes session current, client 2 follows.
+send1 'display-message -p "C1A #{active_window_index} #{local_active_window} #{window_index}"'
+wait_for "$OUT1" 'C1A 0 0 0'
+send1 'select-window -t :1'
+wait_for "$OUT2" '%session-window-changed $0 @1'
+send2 'display-message -p "C2A #{active_window_index} #{local_active_window} #{window_index}"'
+wait_for "$OUT2" 'C2A 1 0 1'
+check_server 'aw:' '#{window_index}' '1'
+
+# Local selection changes only client 1 and becomes the default command target.
+send1 'select-window -L'
+send1 'select-window -t :2'
+send1 'display-message -p "C1B #{active_window_index} #{local_active_window} #{window_index}"'
+wait_for "$OUT1" 'C1B 2 1 2'
+send2 'display-message -p "C2B #{active_window_index} #{local_active_window} #{window_index}"'
+wait_for "$OUT2" 'C2B 1 0 1'
+check_server 'aw:' '#{window_index}' '1'
+
+# Local last-window history is independent of the session shared stack.
+send1 'last-window'
+send1 'display-message -p "C1C #{active_window_index} #{window_index}"'
+wait_for "$OUT1" 'C1C 1 1'
+send1 'next-window'
+send1 'display-message -p "C1D #{active_window_index} #{window_index}"'
+wait_for "$OUT1" 'C1D 2 2'
+check_server 'aw:' '#{window_index}' '1'
+
+# Session switches preserve per-session local selections.
+send1 'switch-client -t aw2'
+send1 'select-window -L'
+send1 'select-window -t :1'
+send1 'display-message -p "C1E #{session_name} #{active_window_index} #{local_active_window}"'
+wait_for "$OUT1" 'C1E aw2 1 1'
+send1 'switch-client -t aw'
+send1 'display-message -p "C1F #{session_name} #{active_window_index} #{local_active_window}"'
+wait_for "$OUT1" 'C1F aw 2 1'
+
+# Returning to shared mode immediately follows the session current window.
+send1 'select-window -S'
+send1 'display-message -p "C1G #{active_window_index} #{local_active_window} #{window_index}"'
+wait_for "$OUT1" 'C1G 1 0 1'
+
+# Invalid local windows recover to a valid session window without changing curw.
+send1 'select-window -L'
+send1 'select-window -t :2'
+$TMUX kill-window -t aw:2 || fail 'kill-window failed'
+send1 'display-message -p "C1H #{active_window_index} #{local_active_window} #{window_index}"'
+wait_for "$OUT1" 'C1H 1 1 1'
+check_server 'aw:' '#{window_index}' '1'
+
+# Creating a window without -d in local mode selects it locally only.
+send1 'new-window -n w3'
+send1 'display-message -p "C1I #{local_active_window} #{window_name}"'
+wait_for "$OUT1" 'C1I 1 w3'
+send2 'display-message -p "C2C #{local_active_window} #{window_name}"'
+wait_for "$OUT2" 'C2C 0 w1'
+check_server 'aw:' '#{window_name}' 'w1'
+
+exit 0

resize.c

@@ -348,10 +348,10 @@ recalculate_size_skip_client(struct client *loop, __unused int type,
 	 * is not the current window - this is used for aggressive-resize.
 	 * Otherwise skip any session that doesn't contain the window.
 	 */
-	if (loop->session->curw == NULL)
+	if (active_get_effective_window(loop, loop->session) == NULL)
 		return (1);
 	if (current)
-		return (loop->session->curw->window != w);
+		return (active_get_effective_window(loop, loop->session) != w);
 	return (session_has(loop->session, w) == 0);
 }
 

screen-redraw.c

@@ -295,7 +295,7 @@ static void
 redraw_set_context(struct client *c, struct redraw_build_ctx *bctx)
 {
 	struct session	*s = c->session;
-	struct window	*w = s->curw->window;
+	struct window	*w = active_get_effective_window(c, s);
 
 	memset(bctx, 0, sizeof *bctx);
 	bctx->c = c;
@@ -966,7 +966,7 @@ static struct redraw_scene *
 redraw_make_scene(struct client *c)
 {
 	struct session			*s = c->session;
-	struct window			*w = s->curw->window;
+	struct window			*w = active_get_effective_window(c, s);
 	struct redraw_build_ctx		 bctx;
 	struct redraw_scene		*scene;
 	struct redraw_build_cell	*bc, *last;
@@ -1076,7 +1076,7 @@ static struct redraw_scene *
 redraw_get_scene(struct client *c)
 {
 	struct redraw_scene	*scene = c->redraw_scene;
-	struct window		*w = c->session->curw->window;
+	struct window		*w = active_get_effective_window(c, c->session);
 	const char		*reason = NULL;
 	u_int			 ox, oy, sx, sy;
 
@@ -1137,7 +1137,7 @@ redraw_get_default_border_style(struct redraw_draw_ctx *dctx,
 	struct grid_cell	*dgc = &dctx->default_gc;
 
 	if (~dctx->flags & REDRAW_DEFAULT_SET) {
-		ft = format_create_defaults(NULL, c, s, s->curw, NULL);
+		ft = format_create_defaults(NULL, c, s, NULL, NULL);
 		memcpy(dgc, &grid_default_cell, sizeof *dgc);
 		style_add(dgc, oo, "pane-border-style", ft);
 		format_free(ft);
@@ -1592,14 +1592,16 @@ redraw_set_draw_context(struct redraw_draw_ctx *dctx,
 	struct session	*s = c->session;
 	struct options	*oo = s->options;
 	struct tty	*tty = &c->tty;
+	struct winlink	*wl;
 	u_int		 lines;
 
 	memset(dctx, 0, sizeof *dctx);
 	dctx->scene = scene;
 
-	if (server_is_marked(s, s->curw, marked_pane.wp))
+	wl = active_get_effective_winlink(c, s);
+	if (server_is_marked(s, wl, marked_pane.wp))
 		dctx->marked = marked_pane.wp;
-	dctx->active = s->curw->window->active;
+	dctx->active = active_get_effective_window(c, s)->active;
 
 	lines = status_line_size(c);
 	if (options_get_number(oo, "status-position") == 0)
@@ -1672,7 +1674,7 @@ redraw_draw(struct client *c, struct window_pane *wp, int flags)
 {
 	struct redraw_draw_ctx	 dctx;
 	struct session		*s = c->session;
-	struct window		*w = s->curw->window;
+	struct window		*w = active_get_effective_window(c, s);
 	struct tty		*tty = &c->tty;
 	struct screen		*sl;
 	struct redraw_scene	*scene;
@@ -1872,7 +1874,7 @@ redraw_screen(struct client *c)
 			flags |= REDRAW_OVERLAY;
 		if (c->flags & CLIENT_REDRAWMENU)
 			flags |= REDRAW_MENU;
-		if (c->session->curw->window->menu != NULL)
+		if (active_get_effective_window(c, c->session)->menu != NULL)
 			flags |= REDRAW_MENU;
 		if (flags != 0)
 			redraw_draw(c, NULL, flags);
@@ -1884,7 +1886,7 @@ void
 redraw_pane(struct client *c, struct window_pane *wp)
 {
 	redraw_draw(c, wp, REDRAW_PANE|REDRAW_PANE_SCROLLBAR);
-	if (c->session->curw->window->menu != NULL)
+	if (active_get_effective_window(c, c->session)->menu != NULL)
 		redraw_draw(c, NULL, REDRAW_MENU);
 }
 

screen-write.c

@@ -142,7 +142,7 @@ screen_write_set_client_cb(struct tty_ctx *ttyctx, struct client *c)
 		return (0);
 	}
 
-	if (c->session->curw->window != wp->window)
+	if (active_get_effective_window(c, c->session) != wp->window)
 		return (0);
 	if (wp->layout_cell == NULL)
 		return (0);

server-client.c

@@ -105,7 +105,7 @@ server_client_set_overlay(struct client *c, u_int delay,
 		c->tty.flags |= TTY_FREEZE;
 	if (c->overlay_mode == NULL)
 		c->tty.flags |= TTY_NOCURSOR;
-	window_update_focus(c->session->curw->window);
+	window_update_focus(active_get_effective_window(c, c->session));
 	server_redraw_client(c);
 }
 
@@ -132,7 +132,7 @@ server_client_clear_overlay(struct client *c)
 
 	c->tty.flags &= ~(TTY_FREEZE|TTY_NOCURSOR);
 	if (c->session != NULL)
-		window_update_focus(c->session->curw->window);
+		window_update_focus(active_get_effective_window(c, c->session));
 	server_redraw_client(c);
 }
 
@@ -376,7 +376,8 @@ server_client_attached_lost(struct client *c)
 		found = NULL;
 		TAILQ_FOREACH(loop, &clients, entry) {
 			s = loop->session;
-			if (loop == c || s == NULL || s->curw->window != w)
+			if (loop == c || s == NULL ||
+			    active_get_effective_window(loop, s) != w)
 				continue;
 			if (found == NULL || timercmp(&loop->activity_time,
 			    &found->activity_time, >))
@@ -457,15 +458,15 @@ server_client_set_session(struct client *c, struct session *s)
 	c->flags |= CLIENT_FOCUSED;
 
 	if (old != NULL && old->curw != NULL)
-		window_update_focus(old->curw->window);
+		window_update_focus(active_get_effective_window(c, old));
 	if (s != NULL) {
-		s->curw->window->latest = c;
+		active_get_effective_window(c, s)->latest = c;
 		recalculate_sizes();
-		window_update_focus(s->curw->window);
+		window_update_focus(active_get_effective_window(c, s));
 		session_update_activity(s, NULL);
 		session_theme_changed(s);
 		gettimeofday(&s->last_attached_time, NULL);
-		s->curw->flags &= ~WINLINK_ALERTFLAGS;
+		active_get_effective_winlink(c, s)->flags &= ~WINLINK_ALERTFLAGS;
 		alerts_check_session(s);
 		tty_update_client_offset(c);
 		status_timer_start(c);
@@ -490,6 +491,7 @@ server_client_lost(struct client *c)
 	server_client_clear_overlay(c);
 	status_prompt_clear(c);
 	status_message_clear(c);
+	active_remove_client(c);
 
 	RB_FOREACH_SAFE(cf, client_files, &c->files, cf1) {
 		cf->error = EINTR;
@@ -675,7 +677,7 @@ server_client_in_scrollbar_area(struct window_pane *wp, int px, int py)
 static void
 server_client_update_scrollbar_hover(struct client *c, int type, int px, int py)
 {
-	struct window		*w = c->session->curw->window;
+	struct window		*w = active_get_effective_window(c, c->session);
 	struct window_pane	*wp;
 
 	if (type != KEYC_TYPE_MOUSEMOVE)
@@ -848,7 +850,7 @@ server_client_check_mouse(struct client *c, struct key_event *event)
 {
 	struct mouse_event		*m = &event->m;
 	struct session			*s = c->session, *fs;
-	struct window			*w = s->curw->window;
+	struct window			*w = active_get_effective_window(c, s);
 	struct winlink			*fwl;
 	struct window_pane		*wp, *fwp, *lwp = NULL;
 	u_int				 x, y, sx, sy, px, py, n, sl_mpos = 0;
@@ -1346,7 +1348,7 @@ server_client_update_latest(struct client *c)
 
 	if (c->session == NULL)
 		return;
-	w = c->session->curw->window;
+	w = active_get_effective_window(c, c->session);
 
 	if (w->latest == c)
 		return;
@@ -1410,7 +1412,7 @@ server_client_key_callback(struct cmdq_item *item, void *data)
 	/* Check the client is good to accept input. */
 	if (s == NULL || (c->flags & CLIENT_UNATTACHEDFLAGS))
 		goto out;
-	wl = s->curw;
+	wl = active_get_effective_winlink(c, s);
 
 	/* Update the activity timer. */
 	memcpy(&c->last_activity_time, &c->activity_time,
@@ -1664,7 +1666,7 @@ out:
 static int
 server_client_handle_menu_key(struct client *c, struct key_event *event)
 {
-	struct window		*w = c->session->curw->window;
+	struct window		*w = active_get_effective_window(c, c->session);
 	struct key_event	 new_event;
 	struct mouse_event	*m;
 	u_int			 ox, oy, sx, sy;
@@ -1701,6 +1703,7 @@ server_client_handle_key0(struct client *c, struct key_event *event,
 {
 	struct session		*s = c->session;
 	struct cmdq_item	*item;
+	struct window		*w;
 	struct window_pane	*wp;
 
 	/* Check the client is good to accept input. */
@@ -1756,9 +1759,10 @@ server_client_handle_key0(struct client *c, struct key_event *event,
 			}
 		}
 
-		wp = s->curw->window->active;
+		w = active_get_effective_window(c, s);
+		wp = w->active;
 		if (wp == NULL || !window_pane_has_prompt(wp)) {
-			TAILQ_FOREACH(wp, &s->curw->window->panes, entry) {
+			TAILQ_FOREACH(wp, &w->panes, entry) {
 				if (window_pane_has_prompt(wp) &&
 				    window_pane_is_visible(wp))
 					break;
@@ -2100,7 +2104,7 @@ static void
 server_client_reset_state(struct client *c)
 {
 	struct tty		*tty = &c->tty;
-	struct window		*w = c->session->curw->window;
+	struct window		*w = active_get_effective_window(c, c->session);
 	struct window_pane	*wp = w->active, *loop;
 	struct screen		*s = NULL;
 	struct options		*oo = c->session->options;
@@ -2341,7 +2345,7 @@ server_client_redraw_timer(__unused int fd, __unused short events,
 static void
 server_client_check_modes(struct client *c)
 {
-	struct window			*w = c->session->curw->window;
+	struct window			*w;
 	struct window_pane		*wp;
 	struct window_mode_entry	*wme;
 
@@ -2349,6 +2353,7 @@ server_client_check_modes(struct client *c)
 		return;
 	if (~c->flags & CLIENT_REDRAWSTATUS)
 		return;
+	w = active_get_effective_window(c, c->session);
 	TAILQ_FOREACH(wp, &w->panes, entry) {
 		wme = TAILQ_FIRST(&wp->modes);
 		if (wme != NULL && wme->mode->update != NULL)
@@ -2361,7 +2366,7 @@ static int
 server_client_any_pane_redraw(struct client *c)
 {
 	struct session		*s = c->session;
-	struct window		*w = s->curw->window;
+	struct window		*w = active_get_effective_window(c, s);
 	struct window_pane	*wp;
 
 	if (c->flags & CLIENT_REDRAWWINDOW)
@@ -2379,7 +2384,7 @@ server_client_check_redraw(struct client *c)
 {
 	struct session		*s = c->session;
 	struct tty		*tty = &c->tty;
-	struct window		*w = s->curw->window;
+	struct window		*w = active_get_effective_window(c, s);
 	struct window_pane	*wp;
 	int			 needed, tflags, mode = tty->mode;
 	struct timeval		 tv = { .tv_usec = 1000 };
@@ -2510,14 +2515,15 @@ static void
 server_client_set_path(struct client *c)
 {
 	struct session	*s = c->session;
+	struct window	*w = active_get_effective_window(c, s);
 	const char	*path;
 
-	if (s->curw == NULL || s->curw->window->active == NULL)
+	if (w == NULL || w->active == NULL)
 		return;
-	if (s->curw->window->active->base.path == NULL)
+	if (w->active->base.path == NULL)
 		path = "";
 	else
-		path = s->curw->window->active->base.path;
+		path = w->active->base.path;
 	if (c->path == NULL || strcmp(path, c->path) != 0) {
 		free(c->path);
 		c->path = xstrdup(path);
@@ -2530,11 +2536,12 @@ static void
 server_client_set_progress_bar(struct client *c)
 {
 	struct session		*s = c->session;
+	struct window		*w = active_get_effective_window(c, s);
 	struct progress_bar	*pane_pb;
 
-	if (s->curw == NULL || s->curw->window->active == NULL)
+	if (w == NULL || w->active == NULL)
 		return;
-	pane_pb = &s->curw->window->active->base.progress_bar;
+	pane_pb = &w->active->base.progress_bar;
 	if (pane_pb->state == c->progress_bar.state &&
 	    pane_pb->progress == c->progress_bar.progress)
 		return;
@@ -3120,7 +3127,7 @@ server_client_print(struct client *c, int parse, struct evbuffer *evb)
 		goto out;
 	}
 
-	wp = c->session->curw->window->active;
+	wp = active_get_effective_window(c, c->session)->active;
 	wme = TAILQ_FIRST(&wp->modes);
 	if (wme == NULL || wme->mode != &window_view_mode)
 		window_pane_set_mode(wp, NULL, &window_view_mode, NULL, NULL,

server-fn.c

@@ -122,8 +122,7 @@ server_redraw_window(struct window *w)
 
 	TAILQ_FOREACH(c, &clients, entry) {
 		if (c->session != NULL &&
-		    c->session->curw != NULL &&
+		    active_get_effective_window(c, c->session) == w)
-		    c->session->curw->window == w)
 			server_redraw_client(c);
 	}
 }
@@ -135,8 +134,7 @@ server_redraw_window_menu(struct window *w)
 
 	TAILQ_FOREACH(c, &clients, entry) {
 		if (c->session != NULL &&
-		    c->session->curw != NULL &&
+		    active_get_effective_window(c, c->session) == w)
-		    c->session->curw->window == w)
 			c->flags |= CLIENT_REDRAWMENU;
 	}
 }
@@ -148,8 +146,7 @@ server_redraw_window_borders(struct window *w)
 
 	TAILQ_FOREACH(c, &clients, entry) {
 		if (c->session != NULL &&
-		    c->session->curw != NULL &&
+		    active_get_effective_window(c, c->session) == w)
-		    c->session->curw->window == w)
 			c->flags |= CLIENT_REDRAWBORDERS;
 	}
 }

session.c

@@ -203,6 +203,7 @@ session_destroy(struct session *s, int notify, const char *from)
 	if (s->curw == NULL)
 		return;
 	s->curw = NULL;
+	active_remove_session(s);
 
 	RB_REMOVE(sessions, &sessions, s);
 	if (notify)

tmux.1

@@ -4026,12 +4026,22 @@ and
 .Ic swap\-window .
 .Tg selectw
 .It Xo Ic select\-window
-.Op Fl lnpT
+.Op Fl LlnpST
 .Op Fl t Ar target\-window
 .Xc
 .D1 Pq alias: Ic selectw
 Select the window at
 .Ar target\-window .
+.Fl L
+makes the attached client use a local current window for the target session.
+Window navigation from that client then changes only that client's effective
+window and leaves the session current window unchanged.
+.Fl S
+returns the client to the shared session current window.
+Without
+.Fl L ,
+the current window is shared by the session and stored in the session.
+.Pp
 .Fl l ,
 .Fl n
 and
@@ -7177,7 +7187,10 @@ will be replaced by
 The following variables are available, where appropriate:
 .Bl -column "XXXXXXXXXXXXXXXXXXX" "XXXXX"
 .It Sy "Variable name" Ta Sy "Alias" Ta Sy "Replaced with"
-.It Li "active_window_index" Ta "" Ta "Index of active window in session"
+.It Li "active_window_id" Ta "" Ta "ID of effective active window"
+.It Li "active_window_index" Ta "" Ta "Index of effective active window"
+.It Li "local_active_window" Ta "" Ta "1 if client has local window selection"
+.It Li "active_window_mode" Ta "" Ta "Window selection mode, shared or local"
 .It Li "alternate_on" Ta "" Ta "1 if pane is in alternate screen"
 .It Li "alternate_saved_x" Ta "" Ta "Saved cursor X in alternate screen"
 .It Li "alternate_saved_y" Ta "" Ta "Saved cursor Y in alternate screen"
@@ -7392,7 +7405,7 @@ The following variables are available, where appropriate:
 .It Li "uid" Ta "" Ta "Server UID"
 .It Li "user" Ta "" Ta "Server user"
 .It Li "version" Ta "" Ta "Server version"
-.It Li "window_active" Ta "" Ta "1 if window active"
+.It Li "window_active" Ta "" Ta "1 if window is the effective active window"
 .It Li "window_active_clients" Ta "" Ta "Number of clients viewing this window"
 .It Li "window_active_clients_list" Ta "" Ta "List of clients viewing this window"
 .It Li "window_active_sessions" Ta "" Ta "Number of sessions on which this window is active"

tmux.h

@@ -2741,6 +2741,32 @@ void	 events_fire_window(const char *, struct window *);
 void	 events_fire_pane(const char *, struct window_pane *);
 void	 events_fire_winlink(const char *, struct winlink *);
 
+/* active.c */
+enum active_window_mode {
+	ACTIVE_SHARED,
+	ACTIVE_LOCAL
+};
+int		 active_is_local_window(struct client *, struct session *);
+void		 active_set_local_window(struct client *, struct session *,
+		     enum active_window_mode);
+struct winlink	*active_get_effective_winlink(struct client *,
+		     struct session *);
+struct window	*active_get_effective_window(struct client *,
+		     struct session *);
+int		 active_select_window(struct client *, struct session *,
+		     struct winlink *);
+int		 active_select_window_index(struct client *, struct session *, int);
+int		 active_next_window(struct client *, struct session *, int);
+int		 active_previous_window(struct client *, struct session *, int);
+int		 active_last_window(struct client *, struct session *);
+void		 active_remove_client(struct client *);
+void		 active_remove_session(struct session *);
+void		 active_remove_window(struct window *);
+int		 active_is_effective_window(struct client *, struct session *,
+		     struct winlink *);
+int		 active_is_last_window(struct client *, struct session *,
+		     struct winlink *);
+
 /* format-draw.c */
 void	 format_draw(struct screen_write_ctx *, const struct grid_cell *,
 	     u_int, const char *, struct style_ranges *, int);
@@ -3733,7 +3759,7 @@ int		 window_pane_is_visible(struct window_pane *);
 int		 window_pane_exited(struct window_pane *);
 u_int		 window_pane_search(struct window_pane *, const char *, int,
 		     int);
-const char	*window_printable_flags(struct winlink *, int);
+const char	*window_printable_flags(struct client *, struct winlink *, int);
 const char      *window_pane_printable_flags(struct window_pane *);
 struct window_pane *window_pane_find_up(struct window_pane *);
 struct window_pane *window_pane_find_down(struct window_pane *);

tty-keys.c

@@ -1007,12 +1007,12 @@ complete_key:
 	/* Check for focus events. */
 	if (key == KEYC_FOCUS_OUT) {
 		c->flags &= ~CLIENT_FOCUSED;
-		window_update_focus(c->session->curw->window);
+		window_update_focus(active_get_effective_window(c, c->session));
 		events_fire_client("client-focus-out", c);
 	} else if (key == KEYC_FOCUS_IN) {
 		c->flags |= CLIENT_FOCUSED;
 		events_fire_client("client-focus-in", c);
-		window_update_focus(c->session->curw->window);
+		window_update_focus(active_get_effective_window(c, c->session));
 	}
 
 	/* Fire the key. */

tty.c

@@ -937,7 +937,7 @@ int
 tty_window_bigger(struct tty *tty)
 {
 	struct client	*c = tty->client;
-	struct window	*w = c->session->curw->window;
+	struct window	*w = active_get_effective_window(c, c->session);
 
 	return (tty->sx < w->sx || tty->sy - status_line_size(c) < w->sy);
 }
@@ -959,7 +959,7 @@ static int
 tty_window_offset1(struct tty *tty, u_int *ox, u_int *oy, u_int *sx, u_int *sy)
 {
 	struct client		*c = tty->client;
-	struct window		*w = c->session->curw->window;
+	struct window		*w = active_get_effective_window(c, c->session);
 	struct window_pane	*wp = w->active;
 	u_int			 cx, cy, lines;
 
@@ -1026,8 +1026,7 @@ tty_update_window_offset(struct window *w)
 
 	TAILQ_FOREACH(c, &clients, entry) {
 		if (c->session != NULL &&
-		    c->session->curw != NULL &&
+		    active_get_effective_window(c, c->session) == w)
-		    c->session->curw->window == w)
 			tty_update_client_offset(c);
 	}
 }
@@ -1529,7 +1528,7 @@ tty_set_client_cb(struct tty_ctx *ttyctx, struct client *c)
 {
 	struct window_pane	*wp = ttyctx->arg;
 
-	if (c->session->curw->window != wp->window)
+	if (active_get_effective_window(c, c->session) != wp->window)
 		return (0);
 	if (wp->layout_cell == NULL)
 		return (0);

window-border.c

@@ -93,7 +93,7 @@ window_pane_get_border_style(struct window_pane *wp, struct client *c,
 	struct grid_cell	*saved;
 	int			*flag;
 
-	if (wp == c->session->curw->window->active) {
+	if (wp == active_get_effective_window(c, c->session)->active) {
 		flag = &wp->active_border_gc_set;
 		saved = &wp->active_border_gc;
 		option = "pane-active-border-style";
@@ -104,7 +104,7 @@ window_pane_get_border_style(struct window_pane *wp, struct client *c,
 	}
 
 	if (!*flag) {
-		ft = format_create_defaults(NULL, c, s, s->curw, wp);
+		ft = format_create_defaults(NULL, c, s, NULL, wp);
 		style_apply(saved, wp->options, option, ft);
 		format_free(ft);
 		*flag = 1;
@@ -133,7 +133,7 @@ window_make_pane_status(struct window_pane *wp, struct client *c, u_int width,
 		return (0);
 
 	ft = format_create(c, NULL, FORMAT_PANE|wp->id, FORMAT_STATUS);
-	format_defaults(ft, c, c->session, c->session->curw, wp);
+	format_defaults(ft, c, c->session, NULL, wp);
 
 	fmt = options_get_string(wp->options, "pane-border-format");
 	expanded = format_expand_time(ft, fmt);

window-client.c

@@ -266,12 +266,13 @@ window_client_draw_info(__unused void *modedata, void *itemdata,
 	struct window_client_itemdata	*item = itemdata;
 	struct client			*c = item->c;
 	struct screen			*s = ctx->s;
-	struct window			*w = c->session->curw->window;
+	struct window			*w;
 	struct grid_cell		 gc;
 	u_int				 cx = s->cx, cy = s->cy, i;
 	struct format_tree		*ft;
 	char				*expanded;
 
+	w = active_get_effective_window(c, c->session);
 	ft = format_create_defaults(NULL, c, NULL, NULL, NULL);
 
 	screen_write_cursormove(ctx, cx, cy, 0);

window.c

@@ -453,6 +453,7 @@ window_destroy(struct window *w)
 {
 	log_debug("window @%u destroyed (%d references)", w->id, w->references);
 
+	active_remove_window(w);
 	window_unzoom(w, 0);
 	RB_REMOVE(windows, &windows, w);
 
@@ -675,6 +676,7 @@ void
 window_pane_update_focus(struct window_pane *wp)
 {
 	struct client	*c;
+	struct window	*w;
 	int		 focused = 0;
 
 	if (wp != NULL && (~wp->flags & PANE_EXITED)) {
@@ -682,10 +684,12 @@ window_pane_update_focus(struct window_pane *wp)
 			focused = 0;
 		else {
 			TAILQ_FOREACH(c, &clients, entry) {
-				if (c->session != NULL &&
+				if (c->session == NULL)
-				    c->session->attached != 0 &&
+					continue;
+				w = active_get_effective_window(c, c->session);
+				if (c->session->attached != 0 &&
 				    (c->flags & CLIENT_FOCUSED) &&
-				    c->session->curw->window == wp->window &&
+				    w == wp->window &&
 				    c->overlay_draw == NULL &&
 				    wp->window->menu == NULL) {
 					focused = 1;
@@ -1222,7 +1226,7 @@ window_destroy_panes(struct window *w)
 }
 
 const char *
-window_printable_flags(struct winlink *wl, int escape)
+window_printable_flags(struct client *c, struct winlink *wl, int escape)
 {
 	struct session	*s = wl->session;
 	static char	 flags[32];
@@ -1237,9 +1241,9 @@ window_printable_flags(struct winlink *wl, int escape)
 		flags[pos++] = '!';
 	if (wl->flags & WINLINK_SILENCE)
 		flags[pos++] = '~';
-	if (wl == s->curw)
+	if (active_is_effective_window(c, s, wl))
 		flags[pos++] = '*';
-	if (wl == TAILQ_FIRST(&s->lastw))
+	if (active_is_last_window(c, s, wl))
 		flags[pos++] = '-';
 	if (server_check_marked() && wl == marked_pane.wl)
 		flags[pos++] = 'M';