diff --git a/server-client.c b/server-client.c
index 3c14ff87..9ac6088b 100644
--- a/server-client.c
+++ b/server-client.c
@@ -17,6 +17,7 @@
  */
 
 #include <sys/types.h>
+#include <sys/ioctl.h>
 
 #include <event.h>
 #include <fcntl.h>
@@ -95,6 +96,8 @@ server_client_create(int fd)
 	c->tty.mouse.event = MOUSE_EVENT_UP;
 	c->tty.mouse.flags = 0;
 
+	c->flags |= CLIENT_FOCUSED;
+
 	evtimer_set(&c->repeat_timer, server_client_repeat_timer, c);
 
 	for (i = 0; i < ARRAY_LENGTH(&clients); i++) {
@@ -545,7 +548,8 @@ server_client_check_resize(struct window_pane *wp)
 void
 server_client_check_focus(struct window_pane *wp)
 {
-	struct session	*s;
+	u_int		 i;
+	struct client	*c;
 
 	/* If we don't care about focus, forget it. */
 	if (!(wp->base.mode & MODE_FOCUSON))
@@ -560,13 +564,20 @@ server_client_check_focus(struct window_pane *wp)
 		goto not_focused;
 
 	/*
-	 * If our window is the current window in any attached sessions, we're
-	 * focused.
+	 * If our window is the current window in any focused clients with an
+	 * attached session, we're focused.
 	 */
-	RB_FOREACH(s, sessions, &sessions) {
-		if (s->flags & SESSION_UNATTACHED)
+	for (i = 0; i < ARRAY_LENGTH(&clients); i++) {
+		c = ARRAY_ITEM(&clients, i);
+		if (c == NULL || c->session == NULL)
 			continue;
-		if (s->curw->window == wp->window)
+
+		if (!(c->flags & CLIENT_FOCUSED))
+			continue;
+		if (c->session->flags & SESSION_UNATTACHED)
+			continue;
+
+		if (c->session->curw->window == wp->window)
 			goto focused;
 	}
 
diff --git a/tmux.h b/tmux.h
index c905b664..966588cc 100644
--- a/tmux.h
+++ b/tmux.h
@@ -237,6 +237,9 @@ enum key_code {
 	KEYC_KP_ENTER,
 	KEYC_KP_ZERO,
 	KEYC_KP_PERIOD,
+
+	KEYC_FOCUS_IN,
+	KEYC_FOCUS_OUT,
 };
 
 /* Termcap codes. */
@@ -1316,6 +1319,7 @@ struct client {
 #define CLIENT_READONLY 0x800
 #define CLIENT_REDRAWWINDOW 0x1000
 #define CLIENT_CONTROL 0x2000
+#define CLIENT_FOCUSED 0x4000
 	int		 flags;
 
 	struct event	 identify_timer;
diff --git a/tty-keys.c b/tty-keys.c
index 00327bb2..575920e6 100644
--- a/tty-keys.c
+++ b/tty-keys.c
@@ -174,6 +174,10 @@ const struct tty_default_key_raw tty_default_raw_keys[] = {
 	{ "\033[8@", KEYC_END|KEYC_CTRL|KEYC_SHIFT },
 	{ "\033[6@", KEYC_NPAGE|KEYC_CTRL|KEYC_SHIFT },
 	{ "\033[5@", KEYC_PPAGE|KEYC_CTRL|KEYC_SHIFT },
+
+	/* Focus tracking. */
+	{ "\033[I", KEYC_FOCUS_IN },
+	{ "\033[O", KEYC_FOCUS_OUT },
 };
 
 /* Default terminfo(5) keys. */
@@ -559,6 +563,15 @@ complete_key:
 		evtimer_del(&tty->key_timer);
 	tty->flags &= ~TTY_TIMER;
 
+	/* Check for focus events. */
+	if (key == KEYC_FOCUS_OUT) {
+		tty->client->flags &= ~CLIENT_FOCUSED;
+		return (1);
+	} else if (key == KEYC_FOCUS_IN) {
+		tty->client->flags |= CLIENT_FOCUSED;
+		return (1);
+	}
+
 	/* Fire the key. */
 	if (key != KEYC_NONE)
 		server_client_handle_key(tty->client, key);
diff --git a/tty.c b/tty.c
index b5dcf6d3..ab75d948 100644
--- a/tty.c
+++ b/tty.c
@@ -221,7 +221,7 @@ tty_start_tty(struct tty *tty)
 		tty_puts(tty, "\033[?1000l\033[?1006l\033[?1005l");
 
 	if (tty_term_has(tty->term, TTYC_XT))
-		tty_puts(tty, "\033[c\033[>4;1m\033[?1004l");
+		tty_puts(tty, "\033[c\033[>4;1m\033[?1004h");
 
 	tty->cx = UINT_MAX;
 	tty->cy = UINT_MAX;
@@ -284,7 +284,7 @@ tty_stop_tty(struct tty *tty)
 		tty_raw(tty, "\033[?1000l\033[?1006l\033[?1005l");
 
 	if (tty_term_has(tty->term, TTYC_XT))
-		tty_raw(tty, "\033[>4m");
+		tty_raw(tty, "\033[>4m\033[?1004l");
 
 	tty_raw(tty, tty_term_string(tty->term, TTYC_RMCUP));