Turn off scrollbar when pane is in alternate screen, from Michael Grant,

GitHub issue 4231.

layout.c

@@ -292,7 +292,7 @@ layout_fix_panes(struct window *w, struct window_pane *skip)
 	struct window_pane	*wp;
 	struct layout_cell	*lc;
 	int			 status, scrollbars, sb_pos;
-	u_int			 sx, sy, mode;
+	u_int			 sx, sy;
 
 	status = options_get_number(w->options, "pane-border-status");
 	scrollbars = options_get_number(w->options, "pane-scrollbars");
@@ -313,10 +313,7 @@ layout_fix_panes(struct window *w, struct window_pane *skip)
 			sy--;
 		}
 
-		mode = window_pane_mode(wp);
-		if (scrollbars == PANE_SCROLLBARS_ALWAYS ||
-		    (scrollbars == PANE_SCROLLBARS_MODAL &&
-		    mode != WINDOW_PANE_NO_MODE)) {
+		if (window_pane_show_scrollbar(wp, scrollbars)) {
 			if (sb_pos == PANE_SCROLLBARS_LEFT) {
 				sx = sx - PANE_SCROLLBARS_WIDTH;
 				wp->xoff = wp->xoff + PANE_SCROLLBARS_WIDTH;

screen-redraw.c

@@ -137,9 +137,7 @@ screen_redraw_pane_border(struct screen_redraw_ctx *ctx, struct window_pane *wp,
 	}
 
 	/* Are scrollbars enabled? */
-	if (pane_scrollbars == PANE_SCROLLBARS_ALWAYS ||
-	    (pane_scrollbars == PANE_SCROLLBARS_MODAL &&
-	     window_pane_mode(wp) != WINDOW_PANE_NO_MODE))
+	if (window_pane_show_scrollbar(wp, pane_scrollbars))
 		sb_w = PANE_SCROLLBARS_WIDTH;
 
 	/*
@@ -364,9 +362,7 @@ screen_redraw_check_cell(struct screen_redraw_ctx *ctx, u_int px, u_int py,
 		*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 (window_pane_show_scrollbar(wp, pane_scrollbars)) {
 
 			if (pane_status == PANE_STATUS_TOP)
 				line = wp->yoff - 1;
@@ -669,11 +665,9 @@ screen_redraw_pane(struct client *c, struct window_pane *wp,
     int redraw_scrollbar_only)
 {
 	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);
@@ -682,15 +676,7 @@ screen_redraw_pane(struct client *c, struct window_pane *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)
+	if (window_pane_show_scrollbar(wp, ctx.pane_scrollbars))
 		screen_redraw_draw_pane_scrollbar(&ctx, wp);
 
 	tty_reset(&c->tty);
@@ -943,17 +929,8 @@ screen_redraw_draw_pane_scrollbars(struct screen_redraw_ctx *ctx)
 	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))
+		if (window_pane_show_scrollbar(wp, ctx->pane_scrollbars) &&
+		    window_pane_visible(wp))
 			screen_redraw_draw_pane_scrollbar(ctx, wp);
 	}
 }

screen-write.c

@@ -2204,6 +2204,7 @@ screen_write_alternateon(struct screen_write_ctx *ctx, struct grid_cell *gc,
 
 	screen_write_collect_flush(ctx, 0, __func__);
 	screen_alternate_on(ctx->s, gc, cursor);
+	layout_fix_panes(wp->window, NULL);
 
 	screen_write_initctx(ctx, &ttyctx, 1);
 	if (ttyctx.redraw_cb != NULL)
@@ -2223,6 +2224,7 @@ screen_write_alternateoff(struct screen_write_ctx *ctx, struct grid_cell *gc,
 
 	screen_write_collect_flush(ctx, 0, __func__);
 	screen_alternate_off(ctx->s, gc, cursor);
+	layout_fix_panes(wp->window, NULL);
 
 	screen_write_initctx(ctx, &ttyctx, 1);
 	if (ttyctx.redraw_cb != NULL)

screen.c

@@ -111,7 +111,7 @@ screen_reinit(struct screen *s)
 	if (options_get_number(global_options, "extended-keys") == 2)
 		s->mode = (s->mode & ~EXTENDED_KEY_MODES)|MODE_KEYS_EXTENDED;
 
-	if (s->saved_grid != NULL)
+	if (SCREEN_IS_ALTERNATE(s))
 		screen_alternate_off(s, NULL, 0);
 	s->saved_cx = UINT_MAX;
 	s->saved_cy = UINT_MAX;
@@ -147,7 +147,7 @@ screen_free(struct screen *s)
 	if (s->write_list != NULL)
 		screen_write_free_list(s);
 
-	if (s->saved_grid != NULL)
+	if (SCREEN_IS_ALTERNATE(s))
 		grid_destroy(s->saved_grid);
 	grid_destroy(s->grid);
 
@@ -612,7 +612,7 @@ screen_alternate_on(struct screen *s, struct grid_cell *gc, int cursor)
 {
 	u_int	sx, sy;
 
-	if (s->saved_grid != NULL)
+	if (SCREEN_IS_ALTERNATE(s))
 		return;
 	sx = screen_size_x(s);
 	sy = screen_size_y(s);
@@ -641,7 +641,7 @@ screen_alternate_off(struct screen *s, struct grid_cell *gc, int cursor)
 	 * If the current size is different, temporarily resize to the old size
 	 * before copying back.
 	 */
-	if (s->saved_grid != NULL)
+	if (SCREEN_IS_ALTERNATE(s))
 		screen_resize(s, s->saved_grid->sx, s->saved_grid->sy, 0);
 
 	/*
@@ -656,7 +656,7 @@ screen_alternate_off(struct screen *s, struct grid_cell *gc, int cursor)
 	}
 
 	/* If not in the alternate screen, do nothing more. */
-	if (s->saved_grid == NULL) {
+	if (!SCREEN_IS_ALTERNATE(s)) {
 		if (s->cx > screen_size_x(s) - 1)
 			s->cx = screen_size_x(s) - 1;
 		if (s->cy > screen_size_y(s) - 1)

server-client.c

@@ -783,11 +783,7 @@ server_client_check_mouse(struct client *c, struct key_event *event)
 
 			/* Try the scrollbar next to a pane. */
 			sb = options_get_number(wo, "pane-scrollbars");
-			sb_pos = options_get_number(wo,
-			    "pane-scrollbars-position");
-			if (sb == PANE_SCROLLBARS_ALWAYS ||
-			    (sb == PANE_SCROLLBARS_MODAL &&
-			    window_pane_mode(wp) != WINDOW_PANE_NO_MODE))
+			if (window_pane_show_scrollbar(wp, sb))
 				sb_w = PANE_SCROLLBARS_WIDTH;
 			else
 				sb_w = 0;
@@ -806,6 +802,8 @@ server_client_check_mouse(struct client *c, struct key_event *event)
 			if ((pane_status != PANE_STATUS_OFF && py != line) ||
 			    (wp->yoff == 0 && py < wp->sy) ||
 			    (py >= wp->yoff && py < wp->yoff + wp->sy)) {
+				sb_pos = options_get_number(wo,
+				    "pane-scrollbars-position");
 				if ((sb_pos == PANE_SCROLLBARS_RIGHT &&
 				    (px >= wp->xoff + wp->sx &&
 				    px < wp->xoff + wp->sx + sb_w)) ||

tmux.h

@@ -1272,6 +1272,9 @@ TAILQ_HEAD(winlink_stack, winlink);
 #define PANE_SCROLLBARS_WIDTH 1
 #define PANE_SCROLLBARS_PADDING 0
 
+/* True if screen in alternate screen. */
+#define SCREEN_IS_ALTERNATE(s) ((s)->saved_grid != NULL)
+
 /* Layout direction. */
 enum layout_type {
 	LAYOUT_LEFTRIGHT,
@@ -3173,6 +3176,7 @@ void		 window_pane_update_used_data(struct window_pane *,
 void		 window_set_fill_character(struct window *);
 void		 window_pane_default_cursor(struct window_pane *);
 int		 window_pane_mode(struct window_pane *);
+int		 window_pane_show_scrollbar(struct window_pane *, int);
 
 /* layout.c */
 u_int		 layout_count_cells(struct layout_cell *);

window.c

@@ -1726,3 +1726,16 @@ window_pane_mode(struct window_pane *wp)
 	}
 	return (WINDOW_PANE_NO_MODE);
 }
+
+/* Return 1 if scrollbar is or should be displayed. */
+int
+window_pane_show_scrollbar(struct window_pane *wp, int sb_option)
+{
+	if (SCREEN_IS_ALTERNATE(wp->screen))
+		return (0);
+	if (sb_option == PANE_SCROLLBARS_ALWAYS ||
+	    (sb_option == PANE_SCROLLBARS_MODAL &&
+	    window_pane_mode(wp) != WINDOW_PANE_NO_MODE))
+		return (1);
+	return (0);
+}