When the mode-mouse option is on, support dragging to make a selection

in copy mode.

Also support the scroll wheel, although xterm strangely does not ignore
it in application mouse mode, causing redraw artifacts when scrolling up
(other terminals appear to be better behaved).

tmux.1

@@ -2078,10 +2078,8 @@ Key bindings default to emacs.
 .Op Ic on | off
 .Xc
 Mouse state in modes.
-If on,
-.Nm
-will respond to mouse clicks by moving the cursor in copy mode or selecting an
-option in choice mode.
+If on, the mouse may be used to copy a selection by dragging in copy mode, or
+to select an option in choice mode.
 .Pp
 .It Xo Ic monitor-activity
 .Op Ic on | off

tmux.h

@@ -541,7 +541,8 @@ struct mode_key_table {
 #define MODE_KCURSOR 0x4
 #define MODE_KKEYPAD 0x8	/* set = application, clear = number */
 #define MODE_MOUSE 0x10
-#define MODE_WRAP 0x20		/* whether lines wrap */
+#define MODE_MOUSEMOTION 0x20
+#define MODE_WRAP 0x40		/* whether lines wrap */
 
 /*
  * A single UTF-8 character.
@@ -1086,7 +1087,7 @@ struct client {
 
 #define CLIENT_TERMINAL 0x1
 #define CLIENT_PREFIX 0x2
-#define CLIENT_MOUSE 0x4
+/* 0x4 unused */
 #define CLIENT_REDRAW 0x8
 #define CLIENT_STATUS 0x10
 #define CLIENT_REPEAT 0x20	/* allow command to repeat within repeat time */

tty-keys.c

@@ -612,7 +612,8 @@ tty_keys_mouse(const char *buf, size_t len, size_t *size, struct mouse_event *m)
 		return (1);
 	*size = 6;
 
-	log_debug("mouse input is: %.6s", buf);
+	log_debug(
+	    "mouse input: %.6s (%hhu,%hhu/%hhu)", buf, buf[4], buf[5], buf[3]);
 
 	m->b = buf[3];
 	m->x = buf[4];

tty.c

@@ -402,11 +402,18 @@ tty_update_mode(struct tty *tty, int mode)
 		else
 			tty_putcode(tty, TTYC_CIVIS);
 	}
-	if (changed & MODE_MOUSE) {
-		if (mode & MODE_MOUSE)
-			tty_puts(tty, "\033[?1000h");
-		else
-			tty_puts(tty, "\033[?1000l");
+	if (changed & (MODE_MOUSE|MODE_MOUSEMOTION)) {
+		if (mode & MODE_MOUSE) {
+			if (mode & MODE_MOUSEMOTION)
+				tty_puts(tty, "\033[?1003h");
+			else
+				tty_puts(tty, "\033[?1000h");
+		} else {
+			if (mode & MODE_MOUSEMOTION)
+				tty_puts(tty, "\033[?1003l");
+			else
+				tty_puts(tty, "\033[?1000l");
+		}
 	}
 	if (changed & MODE_KKEYPAD) {
 		if (mode & MODE_KKEYPAD)

window-copy.c

@@ -760,17 +760,61 @@ window_copy_mouse(
 {
 	struct window_copy_mode_data	*data = wp->modedata;
 	struct screen			*s = &data->screen;
+	u_int				 i;
+
+	/*
+	 * xterm mouse mode is fairly silly. Buttons are in the bottom two
+	 * bits: 0 button 1; 1 button 2; 2 button 3; 3 buttons released.
+	 *
+	 * Bit 3 is shift; bit 4 is meta; bit 5 control.
+	 *
+	 * Bit 6 is added for mouse buttons 4 and 5.
+	 */
 
-	if ((m->b & 3) == 3)
-		return;
 	if (m->x >= screen_size_x(s))
 		return;
 	if (m->y >= screen_size_y(s))
 		return;
 
-	window_copy_update_cursor(wp, m->x, m->y);
-	if (window_copy_update_selection(wp))
+	/* If mouse wheel (buttons 4 and 5), scroll. */
+	if ((m->b & 64) == 64) {
+		if ((m->b & 3) == 0) {
+			for (i = 0; i < 5; i++)
+				window_copy_cursor_up(wp, 0);
+		} else if ((m->b & 3) == 1) {
+			for (i = 0; i < 5; i++)
+				window_copy_cursor_down(wp, 0);
+		}
+		return;
+	}
+
+	/*
+	 * If already reading motion, move the cursor while buttons are still
+	 * pressed, or stop the selection on their release.
+	 */
+	if (s->mode & MODE_MOUSEMOTION) {
+		if ((m->b & 3) != 3) {
+			window_copy_update_cursor(wp, m->x, m->y);
+			if (window_copy_update_selection(wp))
+				window_copy_redraw_screen(wp);
+		} else {
+			s->mode &= ~MODE_MOUSEMOTION;
+			if (sess != NULL) {
+				window_copy_copy_selection(wp, sess);
+				window_pane_reset_mode(wp);
+			}
+		}
+		return;
+	}
+
+	/* Otherwise i other buttons pressed, start selection and motion. */
+	if ((m->b & 3) != 3) {
+		s->mode |= MODE_MOUSEMOTION;
+
+		window_copy_update_cursor(wp, m->x, m->y);
+		window_copy_start_selection(wp);
 		window_copy_redraw_screen(wp);
+	}
 }
 
 void