Add a terminal feature for enable/disable extended keys (supported by

xterm and mintty) and add an option to make tmux send it. Only forward
extended keys if the application has requested them, even though we use
the CSI u sequence and xterm uses CSI 27 ~ - this is what mintty does as
well.

input.c

@@ -241,6 +241,8 @@ enum input_csi_type {
 	INPUT_CSI_HPA,
 	INPUT_CSI_ICH,
 	INPUT_CSI_IL,
+	INPUT_CSI_MODOFF,
+	INPUT_CSI_MODSET,
 	INPUT_CSI_RCP,
 	INPUT_CSI_REP,
 	INPUT_CSI_RM,
@@ -289,7 +291,9 @@ static const struct input_table_entry input_csi_table[] = {
 	{ 'l', "",  INPUT_CSI_RM },
 	{ 'l', "?", INPUT_CSI_RM_PRIVATE },
 	{ 'm', "",  INPUT_CSI_SGR },
+	{ 'm', ">", INPUT_CSI_MODSET },
 	{ 'n', "",  INPUT_CSI_DSR },
+	{ 'n', ">", INPUT_CSI_MODOFF },
 	{ 'q', " ", INPUT_CSI_DECSCUSR },
 	{ 'q', ">", INPUT_CSI_XDA },
 	{ 'r', "",  INPUT_CSI_DECSTBM },
@@ -1380,6 +1384,19 @@ input_csi_dispatch(struct input_ctx *ictx)
 		if (n != -1 && m != -1)
 			screen_write_cursormove(sctx, m - 1, n - 1, 1);
 		break;
+	case INPUT_CSI_MODSET:
+		n = input_get(ictx, 0, 0, 0);
+		m = input_get(ictx, 1, 0, 0);
+		if (n == 0 || (n == 4 && m == 0))
+			screen_write_mode_clear(sctx, MODE_KEXTENDED);
+		else if (n == 4 && (m == 1 || m == 2))
+			screen_write_mode_set(sctx, MODE_KEXTENDED);
+		break;
+	case INPUT_CSI_MODOFF:
+		n = input_get(ictx, 0, 0, 0);
+		if (n == 4)
+			screen_write_mode_clear(sctx, MODE_KEXTENDED);
+		break;
 	case INPUT_CSI_WINOPS:
 		input_csi_dispatch_winops(ictx);
 		break;
@@ -1593,7 +1610,7 @@ input_csi_dispatch(struct input_ctx *ictx)
 		break;
 	case INPUT_CSI_XDA:
 		n = input_get(ictx, 0, 0, 0);
-		if (n != 0)
+		if (n == 0)
 			input_reply(ictx, "\033P>|tmux %s\033\\", getversion());
 		break;
 

options-table.c

@@ -252,6 +252,14 @@ const struct options_table_entry options_table[] = {
 		  "clients."
 	},
 
+	{ .name = "extended-keys",
+	  .type = OPTIONS_TABLE_FLAG,
+	  .scope = OPTIONS_TABLE_SERVER,
+	  .default_num = 0,
+	  .text = "Whether to request extended key sequences from terminals "
+	          "that support it."
+	},
+
 	{ .name = "focus-events",
 	  .type = OPTIONS_TABLE_FLAG,
 	  .scope = OPTIONS_TABLE_SERVER,
@@ -1053,11 +1061,12 @@ const struct options_table_entry options_table[] = {
 		  "bottom."
 	},
 
-	{ .name = "xterm-keys",
+	{ .name = "xterm-keys", /* no longer used */
 	  .type = OPTIONS_TABLE_FLAG,
 	  .scope = OPTIONS_TABLE_WINDOW,
 	  .default_num = 1,
-	  .text = "Whether xterm-style function key sequences should be sent."
+	  .text = "Whether xterm-style function key sequences should be sent. "
+	          "This option is no longer used."
 	},
 
 	/* Hook options. */

tmux.1

@@ -3225,6 +3225,12 @@ sessions.
 .Op Ic on | off
 .Xc
 If enabled, the server will exit when there are no attached clients.
+.It Xo Ic extended-keys
+.Op Ic on | off
+.Xc
+When enabled, extended keys are requested from the terminal and if supported
+are recognised by
+.Nm .
 .It Xo Ic focus-events
 .Op Ic on | off
 .Xc
@@ -4054,16 +4060,6 @@ option.
 .Xc
 If this option is set, searches will wrap around the end of the pane contents.
 The default is on.
-.Pp
-.It Xo Ic xterm-keys
-.Op Ic on | off
-.Xc
-If this option is set,
-.Nm
-will generate
-.Xr xterm 1 -style
-function key sequences; these have a number included to indicate modifiers such
-as Shift, Alt or Ctrl.
 .El
 .Pp
 Available pane options are:
@@ -5754,6 +5750,8 @@ Disable and enable bracketed paste.
 These are set automatically if the
 .Em XT
 capability is present.
+.It Em \&Dseks , \&Eneks
+Disable and enable extended keys.
 .It Em \&Dsfcs , \&Enfcs
 Disable and enable focus reporting.
 These are set automatically if the

tty-features.c

@@ -190,6 +190,18 @@ static const struct tty_feature tty_feature_sync = {
 	0
 };
 
+/* Terminal supports extended keys. */
+static const char *tty_feature_extkeys_capabilities[] = {
+	"Eneks=\\E[>4;1m",
+	"Dseks=\\E[>4m",
+	NULL
+};
+static const struct tty_feature tty_feature_extkeys = {
+	"extkeys",
+	tty_feature_extkeys_capabilities,
+	0
+};
+
 /* Terminal supports DECSLRM margins. */
 static const char *tty_feature_margins_capabilities[] = {
 	"Enmg=\\E[?69h",
@@ -218,6 +230,7 @@ static const struct tty_feature *tty_features[] = {
 	&tty_feature_ccolour,
 	&tty_feature_clipboard,
 	&tty_feature_cstyle,
+	&tty_feature_extkeys,
 	&tty_feature_focus,
 	&tty_feature_margins,
 	&tty_feature_overline,
@@ -321,7 +334,7 @@ tty_default_features(int *feat, const char *name, u_int version)
 	} table[] = {
 #define TTY_FEATURES_BASE_MODERN_XTERM "256,RGB,bpaste,clipboard,strikethrough,title"
 		{ .name = "mintty",
-		  .features = TTY_FEATURES_BASE_MODERN_XTERM ",ccolour,cstyle,margins,overline"
+		  .features = TTY_FEATURES_BASE_MODERN_XTERM ",ccolour,cstyle,extkeys,margins,overline"
 		},
 		{ .name = "tmux",
 		  .features = TTY_FEATURES_BASE_MODERN_XTERM ",ccolour,cstyle,focus,overline,usstyle"
@@ -333,7 +346,7 @@ tty_default_features(int *feat, const char *name, u_int version)
 		  .features = TTY_FEATURES_BASE_MODERN_XTERM ",cstyle,margins,sync"
 		},
 		{ .name = "XTerm",
-		  .features = TTY_FEATURES_BASE_MODERN_XTERM ",ccolour,cstyle,focus,margins,rectfill"
+		  .features = TTY_FEATURES_BASE_MODERN_XTERM ",ccolour,cstyle,extkeys,focus,margins,rectfill"
 		}
 	};
 	u_int	i;