Support the latest theory for mouse input, this is enabled/disabled with

SM/RM 1006 and is similar in style to SGR input: \033[<b;x;yM or
\033[b;x;ym. From Egmont Koblinger.

input-keys.c

@@ -202,12 +202,25 @@ input_key(struct window_pane *wp, int key)
 void
 input_mouse(struct window_pane *wp, struct session *s, struct mouse_event *m)
 {
-	char			 buf[10];
+	char			 buf[40];
 	size_t			 len;
 	struct paste_buffer	*pb;
 
 	if (wp->screen->mode & ALL_MOUSE_MODES) {
-		if (wp->screen->mode & MODE_MOUSE_UTF8) {
+		/*
+		 * Use the SGR (1006) extension only if the application
+		 * requested it and the underlying terminal also sent the event
+		 * in this format (this is because an old style mouse release
+		 * event cannot be converted into the new SGR format, since the
+		 * released button is unknown). Otherwise pretend that tmux
+		 * doesn't speak this extension, and fall back to the UTF-8
+		 * (1005) extension if the application requested, or to the
+		 * legacy format.
+		 */
+		if (m->sgr && (wp->screen->mode & MODE_MOUSE_SGR)) {
+			len = xsnprintf(buf, sizeof buf, "\033[<%d;%d;%d%c",
+			    m->sgr_xb, m->x + 1, m->y + 1, m->sgr_rel ? 'm' : 'M');
+		} else if (wp->screen->mode & MODE_MOUSE_UTF8) {
 			len = xsnprintf(buf, sizeof buf, "\033[M");
 			len += utf8_split2(m->xb + 32, &buf[len]);
 			len += utf8_split2(m->x + 33, &buf[len]);

input.c

@@ -1260,6 +1260,9 @@ input_csi_dispatch(struct input_ctx *ictx)
 		case 1005:
 			screen_write_mode_clear(&ictx->ctx, MODE_MOUSE_UTF8);
 			break;
+		case 1006:
+			screen_write_mode_clear(&ictx->ctx, MODE_MOUSE_SGR);
+			break;
 		case 47:
 		case 1047:
 			window_pane_alternate_off(wp, &ictx->cell, 0);
@@ -1320,6 +1323,9 @@ input_csi_dispatch(struct input_ctx *ictx)
 		case 1005:
 			screen_write_mode_set(&ictx->ctx, MODE_MOUSE_UTF8);
 			break;
+		case 1006:
+			screen_write_mode_set(&ictx->ctx, MODE_MOUSE_SGR);
+			break;
 		case 47:
 		case 1047:
 			window_pane_alternate_on(wp, &ictx->cell, 0);

screen-write.c

@@ -41,7 +41,6 @@ screen_write_start(
 }
 
 /* Finish writing. */
-/* ARGSUSED */
 void
 screen_write_stop(unused struct screen_write_ctx *ctx)
 {
@@ -56,7 +55,9 @@ screen_write_reset(struct screen_write_ctx *ctx)
 
 	screen_reset_tabs(s);
 	screen_write_scrollregion(ctx, 0, screen_size_y(s) - 1);
-	s->mode &= ~(MODE_INSERT|MODE_KCURSOR|MODE_KKEYPAD|ALL_MOUSE_MODES);
+
+	s->mode &= ~(MODE_INSERT|MODE_KCURSOR|MODE_KKEYPAD);
+	s->mode &= ~(ALL_MOUSE_MODES|MODE_MOUSE_UTF8|MODE_MOUSE_SGR);
 
 	screen_write_clearscreen(ctx);
 	screen_write_cursormove(ctx, 0, 0);

tmux.h

@@ -665,7 +665,8 @@ struct mode_key_table {
 #define MODE_MOUSE_BUTTON 0x40
 #define MODE_MOUSE_ANY 0x80
 #define MODE_MOUSE_UTF8 0x100
-#define MODE_BRACKETPASTE 0x200
+#define MODE_MOUSE_SGR 0x200
+#define MODE_BRACKETPASTE 0x400
 
 #define ALL_MOUSE_MODES (MODE_MOUSE_STANDARD|MODE_MOUSE_BUTTON|MODE_MOUSE_ANY)
 
@@ -1153,6 +1154,9 @@ LIST_HEAD(tty_terms, tty_term);
  * - bits 3, 4 and 5 are for keys
  * - bit 6 is set for dragging
  * - bit 7 for buttons 4 and 5
+ *
+ * With the SGR 1006 extension the released button becomes known. Store these
+ * in separate fields and store the value converted to the old format in xb.
  */
 struct mouse_event {
 	u_int	xb;
@@ -1165,6 +1169,10 @@ struct mouse_event {
 	u_int	ly;
 	u_int	sy;
 
+	u_int   sgr;		/* whether the input arrived in SGR format */
+	u_int   sgr_xb;		/* only for SGR: the unmangled button */
+	u_int   sgr_rel;	/* only for SGR: whether it is a release event */
+
 	u_int	button;
 	u_int	clicks;
 

tty-keys.c

@@ -364,8 +364,6 @@ tty_keys_build(struct tty *tty)
 			tty_keys_add(tty, s, tdkc->key);
 
 	}
-
-	tty_keys_add(tty, "abc", 'x');
 }
 
 /* Free the entire key tree. */
@@ -569,7 +567,6 @@ complete_key:
 }
 
 /* Key timer callback. */
-/* ARGSUSED */
 void
 tty_keys_callback(unused int fd, unused short events, void *data)
 {
@@ -590,20 +587,26 @@ tty_keys_mouse(struct tty *tty, const char *buf, size_t len, size_t *size)
 {
 	struct mouse_event	*m = &tty->mouse;
 	struct utf8_data	 utf8data;
-	u_int			 i, value, x, y, b;
+	u_int			 i, value, x, y, b, sgr, sgr_b, sgr_rel;
+	unsigned char		 c;
 
 	/*
 	 * Standard mouse sequences are \033[M followed by three characters
-	 * indicating buttons, X and Y, all based at 32 with 1,1 top-left.
+	 * indicating button, X and Y, all based at 32 with 1,1 top-left.
 	 *
 	 * UTF-8 mouse sequences are similar but the three are expressed as
 	 * UTF-8 characters.
+	 *
+	 * SGR extended mouse sequences are \033[< followed by three numbers in
+	 * decimal and separated by semicolons indicating button, X and Y. A
+	 * trailing 'M' is click or scroll and trailing 'm' release. All are
+	 * based at 0 with 1,1 top-left.
 	 */
 
 	*size = 0;
-	x = y = b  = 0;
+	x = y = b = sgr = sgr_b = sgr_rel = 0;
 
-	/* First three bytes are always \033[M. */
+	/* First two bytes are always \033[. */
 	if (buf[0] != '\033')
 		return (-1);
 	if (len == 1)
@@ -612,15 +615,16 @@ tty_keys_mouse(struct tty *tty, const char *buf, size_t len, size_t *size)
 		return (-1);
 	if (len == 2)
 		return (1);
-	if (buf[2] != 'M')
-		return (-1);
-	if (len == 3)
-		return (1);
 
+	/*
+	 * Third byte is M in old standard and UTF-8 extension, < in SGR
+	 * extension.
+	 */
+	if (buf[2] == 'M') {
 		/* Read the three inputs. */
 		*size = 3;
 		for (i = 0; i < 3; i++) {
-		if (len < *size)
+			if (len <= *size)
 				return (1);
 
 			if (tty->mode & MODE_MOUSE_UTF8) {
@@ -628,15 +632,15 @@ tty_keys_mouse(struct tty *tty, const char *buf, size_t len, size_t *size)
 					if (utf8data.size != 2)
 						return (-1);
 					(*size)++;
-				if (len < *size)
+					if (len <= *size)
 						return (1);
 					utf8_append(&utf8data, buf[*size]);
 					value = utf8_combine(&utf8data);
 				} else
-				value = (unsigned char)buf[*size];
+					value = (u_char) buf[*size];
 				(*size)++;
 			} else {
-			value = (unsigned char)buf[*size];
+				value = (u_char) buf[*size];
 				(*size)++;
 			}
 
@@ -655,7 +659,55 @@ tty_keys_mouse(struct tty *tty, const char *buf, size_t len, size_t *size)
 		b -= 32;
 		x -= 33;
 		y -= 33;
-	log_debug("mouse position: x=%u y=%u b=%u", x, y, b);
+	} else if (buf[2] == '<') {
+		/* Read the three inputs. */
+		*size = 3;
+		while (1) {
+			if (len <= *size)
+				return (1);
+			c = (u_char)buf[(*size)++];
+			if (c == ';')
+				break;
+			if (c < '0' || c > '9')
+				return (-1);
+			sgr_b = 10 * sgr_b + (c - '0');
+		}
+		while (1) {
+			if (len <= *size)
+				return (1);
+			c = (u_char)buf[(*size)++];
+			if (c == ';')
+				break;
+			if (c < '0' || c > '9')
+				return (-1);
+			x = 10 * x + (c - '0');
+		}
+		while (1) {
+			if (len <= *size)
+				return (1);
+			c = (u_char) buf[(*size)++];
+			if (c == 'M' || c == 'm')
+				break;
+			if (c < '0' || c > '9')
+				return (-1);
+			y = 10 * y + (c - '0');
+		}
+		log_debug("mouse input (sgr): %.*s", (int) *size, buf);
+
+		/* Check and return the mouse input. */
+		if (x < 1 || y < 1)
+			return (-1);
+		x--;
+		y--;
+		sgr = 1;
+		sgr_rel = (c == 'm');
+
+		/* Figure out what b would be in old format. */
+		b = sgr_b;
+		if (sgr_rel)
+			b |= 3;
+	} else
+		return (-1);
 
 	/* Fill in mouse structure. */
 	if (~m->event & MOUSE_EVENT_WHEEL) {
@@ -663,6 +715,9 @@ tty_keys_mouse(struct tty *tty, const char *buf, size_t len, size_t *size)
 		m->ly = m->y;
 	}
 	m->xb = b;
+	m->sgr = sgr;
+	m->sgr_xb = sgr_b;
+	m->sgr_rel = sgr_rel;
 	if (b & 64) { /* wheel button */
 		b &= 3;
 		if (b == 0)