Add support for a scrollbar at the side of each pane. New options

pane-scrollbars turn them on or off, pane-scrollbars-position sets the
position (left or right), and pane-scrollbars-style to set the colours.
Mouse support will come later. From Michael Grant in GitHub issue 4221.

10 files changed, 491 insertions, 118 deletions

diff --git a/usr.bin/tmux/layout.c b/usr.bin/tmux/layout.c
index 33d680d37fa..b89e9574f00 100644
--- a/usr.bin/tmux/layout.c
+++ b/usr.bin/tmux/layout.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: layout.c,v 1.48 2021/03/11 06:31:05 nicm Exp $ */
+/* $OpenBSD: layout.c,v 1.49 2024/11/05 09:41:17 nicm Exp $ */
 
 /*
  * Copyright (c) 2009 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -275,7 +275,8 @@ layout_cell_is_bottom(struct window *w, struct layout_cell *lc)
  * the case for the most upper or lower panes only.
  */
 static int
-layout_add_border(struct window *w, struct layout_cell *lc, int status)
+layout_add_horizontal_border(struct window *w, struct layout_cell *lc,
+    int status)
 {
 	if (status == PANE_STATUS_TOP)
 		return (layout_cell_is_top(w, lc));
@@ -290,22 +291,41 @@ layout_fix_panes(struct window *w, struct window_pane *skip)
 {
 	struct window_pane	*wp;
 	struct layout_cell	*lc;
-	int			 status;
+	int			 status, scrollbars, sb_pos;
+	u_int			 sx, sy, mode;
 
 	status = options_get_number(w->options, "pane-border-status");
+	scrollbars = options_get_number(w->options, "pane-scrollbars");
+	sb_pos = options_get_number(w->options, "pane-scrollbars-position");
+
 	TAILQ_FOREACH(wp, &w->panes, entry) {
 		if ((lc = wp->layout_cell) == NULL || wp == skip)
 			continue;
 
 		wp->xoff = lc->xoff;
 		wp->yoff = lc->yoff;
+		sx = lc->sx;
+		sy = lc->sy;
 
-		if (layout_add_border(w, lc, status)) {
+		if (layout_add_horizontal_border(w, lc, status)) {
 			if (status == PANE_STATUS_TOP)
 				wp->yoff++;
-			window_pane_resize(wp, lc->sx, lc->sy - 1);
-		} else
-			window_pane_resize(wp, lc->sx, lc->sy);
+			sy--;
+		}
+
+		mode = window_pane_mode(wp);
+		if (scrollbars == PANE_SCROLLBARS_ALWAYS ||
+		    (scrollbars == PANE_SCROLLBARS_MODAL &&
+		    mode != WINDOW_PANE_NO_MODE)) {
+			if (sb_pos == PANE_SCROLLBARS_LEFT) {
+				sx = sx - PANE_SCROLLBARS_WIDTH;
+				wp->xoff = wp->xoff + PANE_SCROLLBARS_WIDTH;
+			} else /* sb_pos == PANE_SCROLLBARS_RIGHT */
+				sx = sx - PANE_SCROLLBARS_WIDTH;
+			wp->flags |= PANE_REDRAWSCROLLBAR;
+		}
+
+		window_pane_resize(wp, sx, sy);
 	}
 }
 
@@ -337,17 +357,22 @@ layout_resize_check(struct window *w, struct layout_cell *lc,
 {
 	struct layout_cell	*lcchild;
 	u_int			 available, minimum;
-	int			 status;
+	int			 status, scrollbars;
 
 	status = options_get_number(w->options, "pane-border-status");
+	scrollbars = options_get_number(w->options, "pane-scrollbars");
+
 	if (lc->type == LAYOUT_WINDOWPANE) {
 		/* Space available in this cell only. */
 		if (type == LAYOUT_LEFTRIGHT) {
 			available = lc->sx;
-			minimum = PANE_MINIMUM;
+			if (scrollbars)
+				minimum = PANE_MINIMUM + PANE_SCROLLBARS_WIDTH;
+			else
+				minimum = PANE_MINIMUM;
 		} else {
 			available = lc->sy;
-			if (layout_add_border(w, lc, status))
+			if (layout_add_horizontal_border(w, lc, status))
 				minimum = PANE_MINIMUM + 1;
 			else
 				minimum = PANE_MINIMUM;
@@ -873,6 +898,7 @@ layout_split_pane(struct window_pane *wp, enum layout_type type, int size,
 	u_int			sx, sy, xoff, yoff, size1, size2, minimum;
 	u_int			new_size, saved_size, resize_first = 0;
 	int			full_size = (flags & SPAWN_FULLSIZE), status;
+	int			scrollbars;
 
 	/*
 	 * If full_size is specified, add a new cell at the top of the window
@@ -883,6 +909,7 @@ layout_split_pane(struct window_pane *wp, enum layout_type type, int size,
 	else
 		lc = wp->layout_cell;
 	status = options_get_number(wp->window->options, "pane-border-status");
+	scrollbars = options_get_number(wp->window->options, "pane-scrollbars");
 
 	/* Copy the old cell size. */
 	sx = lc->sx;
@@ -893,11 +920,15 @@ layout_split_pane(struct window_pane *wp, enum layout_type type, int size,
 	/* Check there is enough space for the two new panes. */
 	switch (type) {
 	case LAYOUT_LEFTRIGHT:
-		if (sx < PANE_MINIMUM * 2 + 1)
+		if (scrollbars)
+			minimum = PANE_MINIMUM * 2 + PANE_SCROLLBARS_WIDTH;
+		else
+			minimum = PANE_MINIMUM * 2 + 1;
+		if (sx < minimum)
 			return (NULL);
 		break;
 	case LAYOUT_TOPBOTTOM:
-		if (layout_add_border(wp->window, lc, status))
+		if (layout_add_horizontal_border(wp->window, lc, status))
 			minimum = PANE_MINIMUM * 2 + 2;
 		else
 			minimum = PANE_MINIMUM * 2 + 1;
@@ -1054,7 +1085,7 @@ layout_spread_cell(struct window *w, struct layout_cell *parent)
 {
 	struct layout_cell	*lc;
 	u_int			 number, each, size, this;
-	int			 change, changed, status;
+	int			 change, changed, status, scrollbars;
 
 	number = 0;
 	TAILQ_FOREACH (lc, &parent->cells, entry)
@@ -1062,11 +1093,16 @@ layout_spread_cell(struct window *w, struct layout_cell *parent)
 	if (number <= 1)
 		return (0);
 	status = options_get_number(w->options, "pane-border-status");
+	scrollbars = options_get_number(w->options, "pane-scrollbars");
 
-	if (parent->type == LAYOUT_LEFTRIGHT)
-		size = parent->sx;
+	if (parent->type == LAYOUT_LEFTRIGHT) {
+		if (scrollbars)
+			size = parent->sx - PANE_SCROLLBARS_WIDTH;
+		else
+			size = parent->sx;
+	}
 	else if (parent->type == LAYOUT_TOPBOTTOM) {
-		if (layout_add_border(w, parent, status))
+		if (layout_add_horizontal_border(w, parent, status))
 			size = parent->sy - 1;
 		else
 			size = parent->sy;
@@ -1087,7 +1123,7 @@ layout_spread_cell(struct window *w, struct layout_cell *parent)
 			change = each - (int)lc->sx;
 			layout_resize_adjust(w, lc, LAYOUT_LEFTRIGHT, change);
 		} else if (parent->type == LAYOUT_TOPBOTTOM) {
-			if (layout_add_border(w, lc, status))
+			if (layout_add_horizontal_border(w, lc, status))
 				this = each + 1;
 			else
 				this = each;
diff --git a/usr.bin/tmux/options-table.c b/usr.bin/tmux/options-table.c
index 5e729af7d74..469d1c45fb5 100644
--- a/usr.bin/tmux/options-table.c
+++ b/usr.bin/tmux/options-table.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: options-table.c,v 1.183 2024/10/21 12:42:06 nicm Exp $ */
+/* $OpenBSD: options-table.c,v 1.184 2024/11/05 09:41:17 nicm Exp $ */
 
 /*
  * Copyright (c) 2011 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -64,6 +64,12 @@ static const char *options_table_cursor_style_list[] = {
 	"default", "blinking-block", "block", "blinking-underline", "underline",
 	"blinking-bar", "bar", NULL
 };
+static const char *options_table_pane_scrollbars_list[] = {
+	"off", "modal", "on", NULL
+};
+static const char *options_table_pane_scrollbars_position_list[] = {
+	"right", "left", NULL
+};
 static const char *options_table_pane_status_list[] = {
 	"off", "top", "bottom", NULL
 };
@@ -1161,7 +1167,32 @@ const struct options_table_entry options_table[] = {
 	  .text = "The default colour palette for colours zero to 255."
 	},
 
-	{ .name = "popup-style",
+	{ .name = "pane-scrollbars",
+	  .type = OPTIONS_TABLE_CHOICE,
+	  .scope = OPTIONS_TABLE_WINDOW,
+	  .choices = options_table_pane_scrollbars_list,
+	  .default_num = PANE_SCROLLBARS_OFF,
+	  .text = "Pane scrollbar state."
+	},
+
+	{ .name = "pane-scrollbars-style",
+	  .type = OPTIONS_TABLE_STRING,
+	  .scope = OPTIONS_TABLE_WINDOW|OPTIONS_TABLE_PANE,
+	  .default_str = "bg=black,fg=white",
+	  .flags = OPTIONS_TABLE_IS_STYLE,
+	  .separator = ",",
+	  .text = "Style of the pane scrollbar."
+	},
+
+	{ .name = "pane-scrollbars-position",
+	  .type = OPTIONS_TABLE_CHOICE,
+	  .scope = OPTIONS_TABLE_WINDOW,
+	  .choices = options_table_pane_scrollbars_position_list,
+	  .default_num = PANE_SCROLLBARS_RIGHT,
+	  .text = "Pane scrollbar position."
+	},
+
+        { .name = "popup-style",
 	  .type = OPTIONS_TABLE_STRING,
 	  .scope = OPTIONS_TABLE_WINDOW,
 	  .default_str = "default",
diff --git a/usr.bin/tmux/options.c b/usr.bin/tmux/options.c
index e4799942288..8e2107df3cb 100644
--- a/usr.bin/tmux/options.c
+++ b/usr.bin/tmux/options.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: options.c,v 1.70 2024/07/22 15:27:42 nicm Exp $ */
+/* $OpenBSD: options.c,v 1.71 2024/11/05 09:41:17 nicm Exp $ */
 
 /*
  * Copyright (c) 2008 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -1171,7 +1171,9 @@ options_push_changes(const char *name)
 		RB_FOREACH(wp, window_pane_tree, &all_window_panes)
 			colour_palette_from_option(&wp->palette, wp->options);
 	}
-	if (strcmp(name, "pane-border-status") == 0) {
+	if (strcmp(name, "pane-border-status") == 0 ||
+	    strcmp(name, "pane-scrollbars") == 0 ||
+	    strcmp(name, "pane-scrollbars-position") == 0) {
 		RB_FOREACH(w, windows, &windows)
 			layout_fix_panes(w, NULL);
 	}
diff --git a/usr.bin/tmux/screen-redraw.c b/usr.bin/tmux/screen-redraw.c
index af3f1cee11d..cbda4a6954d 100644
--- a/usr.bin/tmux/screen-redraw.c
+++ b/usr.bin/tmux/screen-redraw.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: screen-redraw.c,v 1.99 2024/10/08 09:40:50 nicm Exp $ */
+/* $OpenBSD: screen-redraw.c,v 1.100 2024/11/05 09:41:17 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -30,6 +30,11 @@ static void	screen_redraw_draw_pane(struct screen_redraw_ctx *,
 		    struct window_pane *);
 static void	screen_redraw_set_context(struct client *,
 		    struct screen_redraw_ctx *);
+static void	screen_redraw_draw_pane_scrollbars(struct screen_redraw_ctx *);
+static void	screen_redraw_draw_scrollbar(struct screen_redraw_ctx *,
+		    struct window_pane *, int, int, int, u_int, u_int, u_int);
+static void	screen_redraw_draw_pane_scrollbar(struct screen_redraw_ctx *,
+		    struct window_pane *);
 
 #define START_ISOLATE "\342\201\246"
 #define END_ISOLATE   "\342\201\251"
@@ -113,9 +118,10 @@ screen_redraw_pane_border(struct screen_redraw_ctx *ctx, struct window_pane *wp,
     u_int px, u_int py)
 {
 	struct options	*oo = wp->window->options;
-	int		 split = 0;
 	u_int		 ex = wp->xoff + wp->sx, ey = wp->yoff + wp->sy;
-	int		 pane_status = ctx->pane_status;
+	int		 hsplit = 0, vsplit = 0, pane_status = ctx->pane_status;
+	int		 pane_scrollbars = ctx->pane_scrollbars, sb_w = 0;
+	int		 sb_pos = ctx->pane_scrollbars_pos;
 
 	/* Inside pane. */
 	if (px >= wp->xoff && px < ex && py >= wp->yoff && py < ey)
@@ -125,62 +131,62 @@ screen_redraw_pane_border(struct screen_redraw_ctx *ctx, struct window_pane *wp,
 	switch (options_get_number(oo, "pane-border-indicators")) {
 	case PANE_BORDER_COLOUR:
 	case PANE_BORDER_BOTH:
-		split = 1;
+		hsplit = screen_redraw_two_panes(wp->window, 0);
+		vsplit = screen_redraw_two_panes(wp->window, 1);
 		break;
 	}
 
-	/* Left/right borders. */
-	if (pane_status == PANE_STATUS_OFF) {
-		if (screen_redraw_two_panes(wp->window, 0) && split) {
-			if (wp->xoff == 0 && px == wp->sx && py <= wp->sy / 2)
-				return (SCREEN_REDRAW_BORDER_RIGHT);
-			if (wp->xoff != 0 &&
-			    px == wp->xoff - 1 &&
-			    py > wp->sy / 2)
-				return (SCREEN_REDRAW_BORDER_LEFT);
-		} else {
-			if ((wp->yoff == 0 || py >= wp->yoff - 1) && py <= ey) {
-				if (wp->xoff != 0 && px == wp->xoff - 1)
+	/* Are scrollbars enabled? */
+	if (pane_scrollbars == PANE_SCROLLBARS_ALWAYS ||
+	    (pane_scrollbars == PANE_SCROLLBARS_MODAL &&
+	     window_pane_mode(wp) != WINDOW_PANE_NO_MODE))
+		sb_w = PANE_SCROLLBARS_WIDTH;
+
+	/*
+	 * Left/right borders. The wp->sy / 2 test is to colour only half the
+	 * active window's border when there are two panes.
+	 */
+	if ((wp->yoff == 0 || py >= wp->yoff - 1) && py <= ey) {
+		if (sb_pos == PANE_SCROLLBARS_LEFT) {
+			if (wp->xoff - sb_w == 0 && px == wp->sx + sb_w)
+				if (!hsplit || (hsplit && py <= wp->sy / 2))
+					return (SCREEN_REDRAW_BORDER_RIGHT);
+			if (wp->xoff - sb_w != 0 && px == wp->xoff - sb_w - 1)
+				if (!hsplit || (hsplit && py > wp->sy / 2))
 					return (SCREEN_REDRAW_BORDER_LEFT);
-				if (px == ex)
+		} else { /* sb_pos == PANE_SCROLLBARS_RIGHT */
+			if (wp->xoff == 0 && px == wp->sx + sb_w)
+				if (!hsplit || (hsplit && py <= wp->sy / 2))
 					return (SCREEN_REDRAW_BORDER_RIGHT);
-			}
-		}
-	} else {
-		if ((wp->yoff == 0 || py >= wp->yoff - 1) && py <= ey) {
 			if (wp->xoff != 0 && px == wp->xoff - 1)
-				return (SCREEN_REDRAW_BORDER_LEFT);
-			if (px == ex)
-				return (SCREEN_REDRAW_BORDER_RIGHT);
+				if (!hsplit || (hsplit && py > wp->sy / 2))
+					return (SCREEN_REDRAW_BORDER_LEFT);
 		}
 	}
 
 	/* Top/bottom borders. */
-	if (pane_status == PANE_STATUS_OFF) {
-		if (screen_redraw_two_panes(wp->window, 1) && split) {
-			if (wp->yoff == 0 && py == wp->sy && px <= wp->sx / 2)
-				return (SCREEN_REDRAW_BORDER_BOTTOM);
-			if (wp->yoff != 0 &&
-			    py == wp->yoff - 1 &&
-			    px > wp->sx / 2)
-				return (SCREEN_REDRAW_BORDER_TOP);
-		} else {
-			if ((wp->xoff == 0 || px >= wp->xoff - 1) && px <= ex) {
+	if (vsplit && pane_status == PANE_STATUS_OFF && sb_w == 0) {
+		if (wp->yoff == 0 && py == wp->sy && px <= wp->sx / 2)
+			return (SCREEN_REDRAW_BORDER_BOTTOM);
+		if (wp->yoff != 0 && py == wp->yoff - 1 && px > wp->sx / 2)
+			return (SCREEN_REDRAW_BORDER_TOP);
+	} else {
+		if (sb_pos == PANE_SCROLLBARS_LEFT) {
+			if ((wp->xoff - sb_w == 0 || px >= wp->xoff - sb_w) &&
+			    (px <= ex || (sb_w != 0 && px - 1 == ex))) {
+				if (wp->yoff != 0 && py == wp->yoff - 1)
+					return (SCREEN_REDRAW_BORDER_TOP);
+				if (py == ey)
+					return (SCREEN_REDRAW_BORDER_BOTTOM);
+			}
+		} else { /* sb_pos == PANE_SCROLLBARS_RIGHT */
+			if ((wp->xoff == 0 || px >= wp->xoff) &&
+			    (px <= ex || (sb_w != 0 && px - 1 == ex))) {
 				if (wp->yoff != 0 && py == wp->yoff - 1)
 					return (SCREEN_REDRAW_BORDER_TOP);
 				if (py == ey)
 					return (SCREEN_REDRAW_BORDER_BOTTOM);
 			}
-		}
-	} else if (pane_status == PANE_STATUS_TOP) {
-		if ((wp->xoff == 0 || px >= wp->xoff - 1) && px <= ex) {
-			if (wp->yoff != 0 && py == wp->yoff - 1)
-				return (SCREEN_REDRAW_BORDER_TOP);
-		}
-	} else {
-		if ((wp->xoff == 0 || px >= wp->xoff - 1) && px <= ex) {
-			if (py == ey)
-				return (SCREEN_REDRAW_BORDER_BOTTOM);
 		}
 	}
 
@@ -243,8 +249,12 @@ screen_redraw_type_of_cell(struct screen_redraw_ctx *ctx, u_int px, u_int py)
 		return (CELL_OUTSIDE);
 
 	/*
-	 * Construct a bitmask of whether the cells to the left (bit 4), right,
+	 * Construct a bitmask of whether the cells to the left (bit 8), right,
 	 * top, and bottom (bit 1) of this cell are borders.
+	 *
+	 * bits 8 4 2 1:     2
+	 *		   8 + 4
+	 *		     1
 	 */
 	if (px == 0 || screen_redraw_cell_border(ctx, px - 1, py))
 		borders |= 8;
@@ -313,8 +323,10 @@ screen_redraw_check_cell(struct screen_redraw_ctx *ctx, u_int px, u_int py,
 	struct window_pane	*wp, *active;
 	int			 pane_status = ctx->pane_status;
 	u_int			 sx = w->sx, sy = w->sy;
-	int			 border;
+	int			 border, pane_scrollbars = ctx->pane_scrollbars;
 	u_int			 right, line;
+	int			 sb_pos = ctx->pane_scrollbars_pos;
+	int			 sb_w = PANE_SCROLLBARS_WIDTH;
 
 	*wpp = NULL;
 
@@ -351,6 +363,35 @@ screen_redraw_check_cell(struct screen_redraw_ctx *ctx, u_int px, u_int py,
 			goto next2;
 		*wpp = wp;
 
+		/* Check if CELL_SCROLLBAR */
+		if (pane_scrollbars == PANE_SCROLLBARS_ALWAYS ||
+		    (pane_scrollbars == PANE_SCROLLBARS_MODAL &&
+		     window_pane_mode(wp) != WINDOW_PANE_NO_MODE)) {
+
+			if (pane_status == PANE_STATUS_TOP)
+				line = wp->yoff - 1;
+			else
+				line = wp->yoff + wp->sy;
+
+			/*
+			 * Check if py could lie within a scrollbar. If the
+			 * pane is at the top then py == 0 to sy; if the pane
+			 * is not at the top, then yoff to yoff + sy.
+			 */
+			if ((pane_status && py != line) ||
+			    (wp->yoff == 0 && py < wp->sy) ||
+			     (py >= wp->yoff && py < wp->yoff + wp->sy)) {
+				/* Check if px lies within a scrollbar. */
+				if ((sb_pos == PANE_SCROLLBARS_RIGHT &&
+				     (px >= wp->xoff + wp->sx &&
+				      px < wp->xoff + wp->sx + sb_w)) ||
+				    (sb_pos == PANE_SCROLLBARS_LEFT &&
+				     (px >= wp->xoff - sb_w &&
+				      px < wp->xoff)))
+					return (CELL_SCROLLBAR);
+			}
+		}
+
 		/*
 		 * If definitely inside, return. If not on border, skip.
 		 * Otherwise work out the cell.
@@ -510,14 +551,13 @@ screen_redraw_draw_pane_status(struct screen_redraw_ctx *ctx)
 
 /* Update status line and change flags if unchanged. */
 static uint64_t
-screen_redraw_update(struct client *c, uint64_t flags)
+screen_redraw_update(struct screen_redraw_ctx *ctx, uint64_t flags)
 {
+	struct client			*c = ctx->c;
 	struct window			*w = c->session->curw->window;
 	struct window_pane		*wp;
-	struct options			*wo = w->options;
 	int				 redraw;
 	enum pane_lines			 lines;
-	struct screen_redraw_ctx	 ctx;
 
 	if (c->message_string != NULL)
 		redraw = status_message_redraw(c);
@@ -531,17 +571,17 @@ screen_redraw_update(struct client *c, uint64_t flags)
 	if (c->overlay_draw != NULL)
 		flags |= CLIENT_REDRAWOVERLAY;
 
-	if (options_get_number(wo, "pane-border-status") != PANE_STATUS_OFF) {
-		screen_redraw_set_context(c, &ctx);
-		lines = options_get_number(wo, "pane-border-lines");
+	if (ctx->pane_status != PANE_STATUS_OFF) {
+		lines = ctx->pane_lines;
 		redraw = 0;
 		TAILQ_FOREACH(wp, &w->panes, entry) {
-			if (screen_redraw_make_pane_status(c, wp, &ctx, lines))
+			if (screen_redraw_make_pane_status(c, wp, ctx, lines))
 				redraw = 1;
 		}
 		if (redraw)
 			flags |= CLIENT_REDRAWBORDERS;
 	}
+
 	return (flags);
 }
 
@@ -568,6 +608,10 @@ screen_redraw_set_context(struct client *c, struct screen_redraw_ctx *ctx)
 	ctx->pane_status = options_get_number(wo, "pane-border-status");
 	ctx->pane_lines = options_get_number(wo, "pane-border-lines");
 
+	ctx->pane_scrollbars = options_get_number(wo, "pane-scrollbars");
+	ctx->pane_scrollbars_pos = options_get_number(wo,
+	    "pane-scrollbars-position");
+
 	tty_window_offset(&c->tty, &ctx->ox, &ctx->oy, &ctx->sx, &ctx->sy);
 
 	log_debug("%s: %s @%u ox=%u oy=%u sx=%u sy=%u %u/%d", __func__, c->name,
@@ -585,11 +629,12 @@ screen_redraw_screen(struct client *c)
 	if (c->flags & CLIENT_SUSPENDED)
 		return;
 
-	flags = screen_redraw_update(c, c->flags);
+	screen_redraw_set_context(c, &ctx);
+
+	flags = screen_redraw_update(&ctx, c->flags);
 	if ((flags & CLIENT_ALLREDRAWFLAGS) == 0)
 		return;
 
-	screen_redraw_set_context(c, &ctx);
 	tty_sync_start(&c->tty);
 	tty_update_mode(&c->tty, c->tty.mode, NULL);
 
@@ -598,10 +643,12 @@ screen_redraw_screen(struct client *c)
 		screen_redraw_draw_borders(&ctx);
 		if (ctx.pane_status != PANE_STATUS_OFF)
 			screen_redraw_draw_pane_status(&ctx);
+		screen_redraw_draw_pane_scrollbars(&ctx);
 	}
 	if (flags & CLIENT_REDRAWWINDOW) {
 		log_debug("%s: redrawing panes", c->name);
 		screen_redraw_draw_panes(&ctx);
+		screen_redraw_draw_pane_scrollbars(&ctx);
 	}
 	if (ctx.statuslines != 0 &&
 	    (flags & (CLIENT_REDRAWSTATUS|CLIENT_REDRAWSTATUSALWAYS))) {
@@ -616,20 +663,35 @@ screen_redraw_screen(struct client *c)
 	tty_reset(&c->tty);
 }
 
-/* Redraw a single pane. */
+/* Redraw a single pane and its scrollbar. */
 void
-screen_redraw_pane(struct client *c, struct window_pane *wp)
+screen_redraw_pane(struct client *c, struct window_pane *wp,
+    int redraw_scrollbar_only)
 {
-	struct screen_redraw_ctx	 ctx;
+	struct screen_redraw_ctx	ctx;
+	int				pane_scrollbars, mode;
 
 	if (!window_pane_visible(wp))
 		return;
+	mode = window_pane_mode(wp);
 
 	screen_redraw_set_context(c, &ctx);
 	tty_sync_start(&c->tty);
 	tty_update_mode(&c->tty, c->tty.mode, NULL);
 
-	screen_redraw_draw_pane(&ctx, wp);
+	if (!redraw_scrollbar_only)
+		screen_redraw_draw_pane(&ctx, wp);
+
+	/*
+	 * Redraw scrollbar if needed. Always redraw scrollbar in a mode because
+	 * if redrawing a pane, it's because pane has scrolled.
+	 */
+	pane_scrollbars = ctx.pane_scrollbars;
+	if (pane_scrollbars == PANE_SCROLLBARS_MODAL &&
+	    mode == WINDOW_PANE_NO_MODE)
+		pane_scrollbars = PANE_SCROLLBARS_OFF;
+	if (pane_scrollbars != PANE_SCROLLBARS_OFF)
+		screen_redraw_draw_pane_scrollbar(&ctx, wp);
 
 	tty_reset(&c->tty);
 }
@@ -675,8 +737,7 @@ screen_redraw_draw_borders_cell(struct screen_redraw_ctx *ctx, u_int i, u_int j)
 	const struct grid_cell	*tmp;
 	struct overlay_ranges	 r;
 	u_int			 cell_type, x = ctx->ox + i, y = ctx->oy + j;
-	int			 arrows = 0, border;
-	int			 isolates;
+	int			 arrows = 0, border, isolates;
 
 	if (c->overlay_check != NULL) {
 		c->overlay_check(c, c->overlay_data, x, y, 1, &r);
@@ -685,7 +746,7 @@ screen_redraw_draw_borders_cell(struct screen_redraw_ctx *ctx, u_int i, u_int j)
 	}
 
 	cell_type = screen_redraw_check_cell(ctx, x, y, &wp);
-	if (cell_type == CELL_INSIDE)
+	if (cell_type == CELL_INSIDE || cell_type == CELL_SCROLLBAR)
 		return;
 
 	if (wp == NULL) {
@@ -870,3 +931,127 @@ screen_redraw_draw_pane(struct screen_redraw_ctx *ctx, struct window_pane *wp)
 		tty_draw_line(tty, s, i, j, width, x, y, &defaults, palette);
 	}
 }
+
+/* Draw the panes scrollbars */
+static void
+screen_redraw_draw_pane_scrollbars(struct screen_redraw_ctx *ctx)
+{
+	struct client		*c = ctx->c;
+	struct window		*w = c->session->curw->window;
+	struct window_pane	*wp;
+
+	log_debug("%s: %s @%u", __func__, c->name, w->id);
+
+	TAILQ_FOREACH(wp, &w->panes, entry) {
+		switch (ctx->pane_scrollbars) {
+		case PANE_SCROLLBARS_OFF:
+			return;
+		case PANE_SCROLLBARS_MODAL:
+			if (window_pane_mode(wp) == WINDOW_PANE_NO_MODE)
+				return;
+			break;
+		case PANE_SCROLLBARS_ALWAYS:
+			break;
+		}
+		if (window_pane_visible(wp))
+			screen_redraw_draw_pane_scrollbar(ctx, wp);
+	}
+}
+
+/* Draw pane scrollbar. */
+void
+screen_redraw_draw_pane_scrollbar(struct screen_redraw_ctx *ctx,
+    struct window_pane *wp)
+{
+	struct screen	*s = wp->screen;
+	double		 percent_view;
+	u_int		 sb = ctx->pane_scrollbars, total_height, sb_h = wp->sy;
+	u_int		 sb_pos = ctx->pane_scrollbars_pos, slider_h, slider_y;
+	u_int		 sb_w = PANE_SCROLLBARS_WIDTH, cm_y, cm_size;
+	int		 sb_x, sb_y = (int)(wp->yoff - ctx->oy); /* sb top */
+
+	if (window_pane_mode(wp) == WINDOW_PANE_NO_MODE) {
+		if (sb == PANE_SCROLLBARS_MODAL)
+			return;
+		/* Show slider at the bottom of the scrollbar. */
+		total_height = screen_size_y(s) + screen_hsize(s);
+		percent_view = (double)sb_h / total_height;
+		slider_h = (double)sb_h * percent_view;
+		slider_y = sb_h - slider_h;
+	} else {
+		if (TAILQ_FIRST(&wp->modes) == NULL)
+			return;
+		if (window_copy_get_current_offset(wp, &cm_y, &cm_size) == 0)
+			return;
+		total_height = cm_size + sb_h;
+		percent_view = (double)sb_h / (cm_size + sb_h);
+		slider_h = (double)sb_h * percent_view;
+		slider_y = (sb_h + 1) * ((double)cm_y / total_height);
+	}
+
+	if (sb_pos == PANE_SCROLLBARS_LEFT)
+		sb_x = (int)wp->xoff - sb_w - ctx->ox;
+	else
+		sb_x = (int)wp->xoff + wp->sx - ctx->ox;
+
+	if (slider_h < 1)
+		slider_h = 1;
+	if (slider_y >= sb_h)
+		slider_y = sb_h - 1;
+
+	screen_redraw_draw_scrollbar(ctx, wp, sb_pos, sb_x, sb_y, sb_h,
+	    slider_h, slider_y);
+}
+
+static void
+screen_redraw_draw_scrollbar(struct screen_redraw_ctx *ctx,
+    struct window_pane *wp, int sb_pos, int sb_x, int sb_y, u_int sb_h,
+    u_int slider_h, u_int slider_y)
+{
+	struct client		*c = ctx->c;
+	struct window		*w = wp->window;
+	struct tty		*tty = &c->tty;
+	struct grid_cell	 gc, slgc, *gcp;
+	u_int			 i, j, sb_w = PANE_SCROLLBARS_WIDTH;
+	u_int			 pad_col = 0;
+	int			 px, py, ox = ctx->ox, oy = ctx->oy;
+	int                      sb_pad = PANE_SCROLLBARS_PADDING, sx = ctx->sx;
+	int			 sy = ctx->sy, xoff = wp->xoff, yoff = wp->yoff;
+
+	/* Set up default style. */
+	style_apply(&gc, w->options, "pane-scrollbars-style", NULL);
+	utf8_set(&gc.data, ' ');
+
+	/* Set up style for slider. */
+	memcpy(&slgc, &gc, sizeof slgc);
+	slgc.bg = gc.fg;
+
+	if (sb_pad != 0) {
+		if (sb_pos == PANE_SCROLLBARS_RIGHT)
+			pad_col = 0;
+		else
+			pad_col = sb_w - 1;
+	}
+
+	for (i = 0; i < sb_w; i++) {
+		for (j = 0; j < sb_h; j++) {
+			px = sb_x + i;
+			py = sb_y + j;
+			if (px < xoff - ox - 1 || px >= sx || px < 0 ||
+			    py < yoff - oy - 1 || py >= sy || py < 0)
+				continue;
+			tty_cursor(tty, px, py);
+			if (sb_pad && i == pad_col) {
+				tty_cell(tty, &grid_default_cell,
+				    &grid_default_cell, NULL, NULL);
+			} else {
+				if (j >= slider_y && j < slider_y + slider_h)
+					gcp = &slgc;
+				else
+					gcp = &gc;
+				tty_cell(tty, gcp, &grid_default_cell, NULL,
+				    NULL);
+			}
+		}
+	}
+}
diff --git a/usr.bin/tmux/screen-write.c b/usr.bin/tmux/screen-write.c
index 47de30213e1..039cab62dd8 100644
--- a/usr.bin/tmux/screen-write.c
+++ b/usr.bin/tmux/screen-write.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: screen-write.c,v 1.228 2024/10/25 15:00:18 nicm Exp $ */
+/* $OpenBSD: screen-write.c,v 1.229 2024/11/05 09:41:17 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -151,7 +151,7 @@ screen_write_set_client_cb(struct tty_ctx *ttyctx, struct client *c)
 		 */
 		log_debug("%s: adding %%%u to deferred redraw", __func__,
 		    wp->id);
-		wp->flags |= PANE_REDRAW;
+		wp->flags |= (PANE_REDRAW|PANE_REDRAWSCROLLBAR);
 		return (-1);
 	}
 
@@ -1178,13 +1178,14 @@ screen_write_deleteline(struct screen_write_ctx *ctx, u_int ny, u_int bg)
 	struct screen	*s = ctx->s;
 	struct grid	*gd = s->grid;
 	struct tty_ctx	 ttyctx;
+	u_int		 sy = screen_size_y(s);
 
 	if (ny == 0)
 		ny = 1;
 
 	if (s->cy < s->rupper || s->cy > s->rlower) {
-		if (ny > screen_size_y(s) - s->cy)
-			ny = screen_size_y(s) - s->cy;
+		if (ny > sy - s->cy)
+			ny = sy - s->cy;
 		if (ny == 0)
 			return;
 
@@ -1376,13 +1377,14 @@ screen_write_linefeed(struct screen_write_ctx *ctx, int wrapped, u_int bg)
 	struct screen		*s = ctx->s;
 	struct grid		*gd = s->grid;
 	struct grid_line	*gl;
+	u_int			 rupper = s->rupper, rlower = s->rlower;
 
 	gl = grid_get_line(gd, gd->hsize + s->cy);
 	if (wrapped)
 		gl->flags |= GRID_LINE_WRAPPED;
 
 	log_debug("%s: at %u,%u (region %u-%u)", __func__, s->cx, s->cy,
-	    s->rupper, s->rlower);
+	    rupper, rlower);
 
 	if (bg != ctx->bg) {
 		screen_write_collect_flush(ctx, 1, __func__);
@@ -1700,6 +1702,9 @@ screen_write_collect_flush(struct screen_write_ctx *ctx, int scroll_only,
 		ttyctx.num = ctx->scrolled;
 		ttyctx.bg = ctx->bg;
 		tty_write(tty_cmd_scrollup, &ttyctx);
+
+		if (ctx->wp != NULL)
+			ctx->wp->flags |= PANE_REDRAWSCROLLBAR;
 	}
 	ctx->scrolled = 0;
 	ctx->bg = 8;
diff --git a/usr.bin/tmux/server-client.c b/usr.bin/tmux/server-client.c
index 75c2f1824a1..1493b6726a5 100644
--- a/usr.bin/tmux/server-client.c
+++ b/usr.bin/tmux/server-client.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: server-client.c,v 1.414 2024/10/08 06:29:44 nicm Exp $ */
+/* $OpenBSD: server-client.c,v 1.415 2024/11/05 09:41:17 nicm Exp $ */
 
 /*
  * Copyright (c) 2009 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -2230,7 +2230,7 @@ server_client_loop(void)
 				server_client_check_pane_resize(wp);
 				server_client_check_pane_buffer(wp);
 			}
-			wp->flags &= ~PANE_REDRAW;
+			wp->flags &= ~(PANE_REDRAW|PANE_REDRAWSCROLLBAR);
 		}
 		check_window_name(w);
 	}
@@ -2662,7 +2662,7 @@ server_client_check_redraw(struct client *c)
 	struct window_pane	*wp;
 	int			 needed, tty_flags, mode = tty->mode;
 	uint64_t		 client_flags = 0;
-	int			 redraw;
+	int			 redraw_pane, redraw_scrollbar_only;
 	u_int			 bit = 0;
 	struct timeval		 tv = { .tv_usec = 1000 };
 	static struct event	 ev;
@@ -2671,12 +2671,13 @@ server_client_check_redraw(struct client *c)
 	if (c->flags & (CLIENT_CONTROL|CLIENT_SUSPENDED))
 		return;
 	if (c->flags & CLIENT_ALLREDRAWFLAGS) {
-		log_debug("%s: redraw%s%s%s%s%s", c->name,
+		log_debug("%s: redraw%s%s%s%s%s%s", c->name,
 		    (c->flags & CLIENT_REDRAWWINDOW) ? " window" : "",
 		    (c->flags & CLIENT_REDRAWSTATUS) ? " status" : "",
 		    (c->flags & CLIENT_REDRAWBORDERS) ? " borders" : "",
 		    (c->flags & CLIENT_REDRAWOVERLAY) ? " overlay" : "",
-		    (c->flags & CLIENT_REDRAWPANES) ? " panes" : "");
+		    (c->flags & CLIENT_REDRAWPANES) ? " panes" : "",
+		    (c->flags & CLIENT_REDRAWSCROLLBARS) ? " scrollbars" : "");
 	}
 
 	/*
@@ -2691,11 +2692,15 @@ server_client_check_redraw(struct client *c)
 		TAILQ_FOREACH(wp, &w->panes, entry) {
 			if (wp->flags & PANE_REDRAW) {
 				needed = 1;
+				client_flags |= CLIENT_REDRAWPANES;
 				break;
 			}
+			if (wp->flags & PANE_REDRAWSCROLLBAR) {
+				needed = 1;
+				client_flags |= CLIENT_REDRAWSCROLLBARS;
+				/* no break - later panes may need redraw */
+			}
 		}
-		if (needed)
-			client_flags |= CLIENT_REDRAWPANES;
 	}
 	if (needed && (left = EVBUFFER_LENGTH(tty->out)) != 0) {
 		log_debug("%s: redraw deferred (%zu left)", c->name, left);
@@ -2708,23 +2713,30 @@ server_client_check_redraw(struct client *c)
 
 		if (~c->flags & CLIENT_REDRAWWINDOW) {
 			TAILQ_FOREACH(wp, &w->panes, entry) {
-				if (wp->flags & PANE_REDRAW) {
+				if (wp->flags & (PANE_REDRAW)) {
 					log_debug("%s: pane %%%u needs redraw",
 					    c->name, wp->id);
 					c->redraw_panes |= (1 << bit);
+				} else if (wp->flags & PANE_REDRAWSCROLLBAR) {
+					log_debug("%s: pane %%%u scrollbar "
+					    "needs redraw", c->name, wp->id);
+					c->redraw_scrollbars |= (1 << bit);
 				}
 				if (++bit == 64) {
 					/*
 					 * If more that 64 panes, give up and
 					 * just redraw the window.
 					 */
-					client_flags &= CLIENT_REDRAWPANES;
+					client_flags &= ~(CLIENT_REDRAWPANES|
+					    CLIENT_REDRAWSCROLLBARS);
 					client_flags |= CLIENT_REDRAWWINDOW;
 					break;
 				}
 			}
 			if (c->redraw_panes != 0)
 				c->flags |= CLIENT_REDRAWPANES;
+			if (c->redraw_scrollbars != 0)
+				c->flags |= CLIENT_REDRAWSCROLLBARS;
 		}
 		c->flags |= client_flags;
 		return;
@@ -2740,19 +2752,32 @@ server_client_check_redraw(struct client *c)
 		 * needs to be redrawn.
 		 */
 		TAILQ_FOREACH(wp, &w->panes, entry) {
-			redraw = 0;
+			redraw_pane = 0;
+			redraw_scrollbar_only = 0;
 			if (wp->flags & PANE_REDRAW)
-				redraw = 1;
-			else if (c->flags & CLIENT_REDRAWPANES)
-				redraw = !!(c->redraw_panes & (1 << bit));
+				redraw_pane = 1;
+			else if (c->flags & CLIENT_REDRAWPANES) {
+				if (c->redraw_panes & (1 << bit))
+					redraw_pane = 1;
+			} else if (c->flags & CLIENT_REDRAWSCROLLBARS) {
+				if (c->redraw_scrollbars & (1 << bit))
+					redraw_scrollbar_only = 1;
+			}
 			bit++;
-			if (!redraw)
+			if (!redraw_pane && !redraw_scrollbar_only)
 				continue;
-			log_debug("%s: redrawing pane %%%u", __func__, wp->id);
-			screen_redraw_pane(c, wp);
+			if (redraw_scrollbar_only) {
+				log_debug("%s: redrawing (scrollbar only) pane "
+				    "%%%u", __func__, wp->id);
+			} else {
+				log_debug("%s: redrawing pane %%%u", __func__,
+				    wp->id);
+			}
+			screen_redraw_pane(c, wp, redraw_scrollbar_only);
 		}
 		c->redraw_panes = 0;
-		c->flags &= ~CLIENT_REDRAWPANES;
+		c->redraw_scrollbars = 0;
+		c->flags &= ~(CLIENT_REDRAWPANES|CLIENT_REDRAWSCROLLBARS);
 	}
 
 	if (c->flags & CLIENT_ALLREDRAWFLAGS) {
diff --git a/usr.bin/tmux/tmux.1 b/usr.bin/tmux/tmux.1
index 6e7aebfbebd..2c70a2c4e17 100644
--- a/usr.bin/tmux/tmux.1
+++ b/usr.bin/tmux/tmux.1
@@ -1,4 +1,4 @@
-.\" $OpenBSD: tmux.1,v 1.967 2024/10/17 17:22:01 nicm Exp $
+.\" $OpenBSD: tmux.1,v 1.968 2024/11/05 09:41:17 nicm Exp $
 .\"
 .\" Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
 .\"
@@ -14,7 +14,7 @@
 .\" IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 .\" OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: October 17 2024 $
+.Dd $Mdocdate: November 5 2024 $
 .Dt TMUX 1
 .Os
 .Sh NAME
@@ -5026,6 +5026,46 @@ and
 .Ql heavy
 will fall back to standard ACS line drawing when UTF-8 is not supported.
 .Pp
+.It Xo Ic pane-scrollbars
+.Op Ic off | modal | on
+.Xc
+When enabled, a character based scrollbar appears on the left or right
+of each pane.
+A filled section of the scrollbar, known as the
+.Ql slider ,
+represents the position and size of the visible part of the pane content.
+.Pp
+If set to
+.Ic on
+the scrollbar is visible all the time.
+If set to
+.Ic modal
+the scrollbar only appears when the pane is in copy mode or view mode.
+When the scrollbar is visible, the pane is narrowed by the width of the
+scrollbar and the text in the pane is reflowed.
+If set to
+.Ic modal ,
+the pane is narrowed only when the scrollbar is visible.
+.Pp
+See also
+.Xr pane-scrollbars-style .
+.Pp
+.It Ic pane-scrollbars-style Ar style
+Set the scrollbars style.
+For how to specify
+.Ar style ,
+see the
+.Sx STYLES
+section.
+The foreground colour is used for the slider, the background for the rest of the
+scrollbar.
+Attributes are ignored.
+.Pp
+.It Xo Ic pane-scrollbars-position
+.Op Ic left | right
+.Xc
+Sets which side of the pane to display pane scrollbars on.
+.Pp
 .It Ic window-status-activity-style Ar style
 Set status line style for windows with an activity alert.
 For how to specify
diff --git a/usr.bin/tmux/tmux.h b/usr.bin/tmux/tmux.h
index dac5d950e4e..5b571fbe11c 100644
--- a/usr.bin/tmux/tmux.h
+++ b/usr.bin/tmux/tmux.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: tmux.h,v 1.1237 2024/10/25 15:32:51 nicm Exp $ */
+/* $OpenBSD: tmux.h,v 1.1238 2024/11/05 09:41:17 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -739,6 +739,7 @@ struct colour_palette {
 #define CELL_RIGHTJOIN 10
 #define CELL_JOIN 11
 #define CELL_OUTSIDE 12
+#define CELL_SCROLLBAR 13
 
 /* Cell borders. */
 #define CELL_BORDERS " xqlkmjwvtun~"
@@ -985,6 +986,9 @@ struct screen_redraw_ctx {
 	int		 pane_status;
 	enum pane_lines	 pane_lines;
 
+	int		 pane_scrollbars;
+	int		 pane_scrollbars_pos;
+
 	struct grid_cell no_pane_gc;
 	int		 no_pane_gc_set;
 
@@ -1103,6 +1107,7 @@ struct window_pane {
 #define PANE_EMPTY 0x800
 #define PANE_STYLECHANGED 0x1000
 #define PANE_UNSEENCHANGES 0x2000
+#define PANE_REDRAWSCROLLBAR 0x4000
 
 	int		 argc;
 	char	       **argv;
@@ -1245,6 +1250,19 @@ TAILQ_HEAD(winlink_stack, winlink);
 #define PANE_STATUS_TOP 1
 #define PANE_STATUS_BOTTOM 2
 
+/* Pane scrollbars option. */
+#define PANE_SCROLLBARS_OFF 0
+#define PANE_SCROLLBARS_MODAL 1
+#define PANE_SCROLLBARS_ALWAYS 2
+
+/* Pane scrollbars position option. */
+#define PANE_SCROLLBARS_RIGHT 0
+#define PANE_SCROLLBARS_LEFT 1
+
+/* Pane scrollbars width and padding. */
+#define PANE_SCROLLBARS_WIDTH 1
+#define PANE_SCROLLBARS_PADDING 0
+
 /* Layout direction. */
 enum layout_type {
 	LAYOUT_LEFTRIGHT,
@@ -1880,13 +1898,15 @@ struct client {
 #define CLIENT_CLIPBOARDBUFFER 0x800000000ULL
 #define CLIENT_BRACKETPASTING 0x1000000000ULL
 #define CLIENT_ASSUMEPASTING 0x2000000000ULL
+#define CLIENT_REDRAWSCROLLBARS 0x4000000000ULL
 #define CLIENT_ALLREDRAWFLAGS		\
 	(CLIENT_REDRAWWINDOW|		\
 	 CLIENT_REDRAWSTATUS|		\
 	 CLIENT_REDRAWSTATUSALWAYS|	\
 	 CLIENT_REDRAWBORDERS|		\
 	 CLIENT_REDRAWOVERLAY|		\
-	 CLIENT_REDRAWPANES)
+	 CLIENT_REDRAWPANES|		\
+	 CLIENT_REDRAWSCROLLBARS)
 #define CLIENT_UNATTACHEDFLAGS	\
 	(CLIENT_DEAD|		\
 	 CLIENT_SUSPENDED|	\
@@ -1913,6 +1933,7 @@ struct client {
 	key_code		 last_key;
 
 	uint64_t		 redraw_panes;
+	uint64_t		 redraw_scrollbars;
 
 	int			 message_ignore_keys;
 	int			 message_ignore_styles;
@@ -3014,7 +3035,7 @@ void	 screen_write_alternateoff(struct screen_write_ctx *,
 
 /* screen-redraw.c */
 void	 screen_redraw_screen(struct client *);
-void	 screen_redraw_pane(struct client *, struct window_pane *);
+void	 screen_redraw_pane(struct client *, struct window_pane *, int);
 
 /* screen.c */
 void	 screen_init(struct screen *, u_int, u_int, u_int);
diff --git a/usr.bin/tmux/window-copy.c b/usr.bin/tmux/window-copy.c
index e1bdea65b5c..148b32f5189 100644
--- a/usr.bin/tmux/window-copy.c
+++ b/usr.bin/tmux/window-copy.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: window-copy.c,v 1.362 2024/10/28 08:16:51 nicm Exp $ */
+/* $OpenBSD: window-copy.c,v 1.363 2024/11/05 09:41:17 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -4319,6 +4319,8 @@ window_copy_redraw_lines(struct window_mode_entry *wme, u_int py, u_int ny)
 		window_copy_write_line(wme, &ctx, i);
 	screen_write_cursormove(&ctx, data->cx, data->cy, 0);
 	screen_write_stop(&ctx);
+
+	wp->flags |= PANE_REDRAWSCROLLBAR;
 }
 
 static void
@@ -5367,8 +5369,7 @@ window_copy_cursor_previous_word_pos(struct window_mode_entry *wme,
 	py = hsize + data->cy - data->oy;
 
 	grid_reader_start(&gr, back_s->grid, px, py);
-	grid_reader_cursor_previous_word(&gr, separators, /* already= */ 0,
-        /* stop_at_eol= */ 1);
+	grid_reader_cursor_previous_word(&gr, separators, 0, 1);
 	grid_reader_get_cursor(&gr, &px, &py);
 	*ppx = px;
 	*ppy = py;
@@ -5481,6 +5482,7 @@ window_copy_scroll_up(struct window_mode_entry *wme, u_int ny)
 		window_copy_write_line(wme, &ctx, screen_size_y(s) - ny - 1);
 	screen_write_cursormove(&ctx, data->cx, data->cy, 0);
 	screen_write_stop(&ctx);
+	wp->flags |= PANE_REDRAWSCROLLBAR;
 }
 
 static void
@@ -5514,6 +5516,7 @@ window_copy_scroll_down(struct window_mode_entry *wme, u_int ny)
 		window_copy_write_line(wme, &ctx, 1);
 	screen_write_cursormove(&ctx, data->cx, data->cy, 0);
 	screen_write_stop(&ctx);
+	wp->flags |= PANE_REDRAWSCROLLBAR;
 }
 
 static void
diff --git a/usr.bin/tmux/window.c b/usr.bin/tmux/window.c
index ab0b49e9a21..e916410608c 100644
--- a/usr.bin/tmux/window.c
+++ b/usr.bin/tmux/window.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: window.c,v 1.295 2024/10/05 12:10:16 nicm Exp $ */
+/* $OpenBSD: window.c,v 1.296 2024/11/05 09:41:17 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -584,11 +584,31 @@ struct window_pane *
 window_get_active_at(struct window *w, u_int x, u_int y)
 {
 	struct window_pane	*wp;
+	int			 pane_scrollbars;
+	u_int			 sb_pos, sb_w, xoff, sx;
+
+	pane_scrollbars = options_get_number(w->options, "pane-scrollbars");
+	sb_pos = options_get_number(w->options, "pane-scrollbars-position");
 
 	TAILQ_FOREACH(wp, &w->panes, entry) {
 		if (!window_pane_visible(wp))
 			continue;
-		if (x < wp->xoff || x > wp->xoff + wp->sx)
+
+		if (pane_scrollbars == PANE_SCROLLBARS_ALWAYS ||
+		    (pane_scrollbars == PANE_SCROLLBARS_MODAL &&
+		     window_pane_mode(wp) != WINDOW_PANE_NO_MODE))
+			sb_w = PANE_SCROLLBARS_WIDTH;
+		else
+			sb_w = 0;
+
+		if (sb_pos == PANE_SCROLLBARS_LEFT) {
+			xoff = wp->xoff - sb_w;
+			sx = wp->sx + sb_w;
+		} else { /* sb_pos == PANE_SCROLLBARS_RIGHT */
+			xoff = wp->xoff;
+			sx = wp->sx + sb_w;
+		}
+		if (x < xoff || x > xoff + sx)
 			continue;
 		if (y < wp->yoff || y > wp->yoff + wp->sy)
 			continue;
@@ -1086,6 +1106,7 @@ window_pane_set_mode(struct window_pane *wp, struct window_pane *swp,
     struct args *args)
 {
 	struct window_mode_entry	*wme;
+	struct window			*w = wp->window;
 
 	if (!TAILQ_EMPTY(&wp->modes) && TAILQ_FIRST(&wp->modes)->mode == mode)
 		return (1);
@@ -1106,9 +1127,10 @@ window_pane_set_mode(struct window_pane *wp, struct window_pane *swp,
 		TAILQ_INSERT_HEAD(&wp->modes, wme, entry);
 		wme->screen = wme->mode->init(wme, fs, args);
 	}
-
 	wp->screen = wme->screen;
-	wp->flags |= (PANE_REDRAW|PANE_CHANGED);
+
+	wp->flags |= (PANE_REDRAW|PANE_REDRAWSCROLLBAR|PANE_CHANGED);
+	layout_fix_panes(w, NULL);
 
 	server_redraw_window_borders(wp->window);
 	server_status_window(wp->window);
@@ -1121,6 +1143,7 @@ void
 window_pane_reset_mode(struct window_pane *wp)
 {
 	struct window_mode_entry	*wme, *next;
+	struct window			*w = wp->window;
 
 	if (TAILQ_EMPTY(&wp->modes))
 		return;
@@ -1141,7 +1164,9 @@ window_pane_reset_mode(struct window_pane *wp)
 		if (next->mode->resize != NULL)
 			next->mode->resize(next, wp->sx, wp->sy);
 	}
-	wp->flags |= (PANE_REDRAW|PANE_CHANGED);
+
+	wp->flags |= (PANE_REDRAW|PANE_REDRAWSCROLLBAR|PANE_CHANGED);
+	layout_fix_panes(w, NULL);
 
 	server_redraw_window_borders(wp->window);
 	server_status_window(wp->window);