diff --git a/menu.c b/menu.c
index 7449d88d..cd361e00 100644
--- a/menu.c
+++ b/menu.c
@@ -181,15 +181,17 @@ menu_mode_cb(__unused struct client *c, void *data, u_int *cx, u_int *cy)
 }
 
 /* Return parts of the input range which are not obstructed by the menu. */
-void
+struct visible_ranges *
 menu_check_cb(__unused struct client *c, void *data, u_int px, u_int py,
-    u_int nx, struct overlay_ranges *r)
+    u_int nx)
 {
 	struct menu_data	*md = data;
 	struct menu		*menu = md->menu;
+	struct visible_ranges	*r;
 
-	server_client_overlay_range(md->px, md->py, menu->width + 4,
-	    menu->count + 2, px, py, nx, r);
+	r = server_client_overlay_range(md->px, md->py, menu->width + 4,
+	    menu->count + 2, px, py, nx);
+	return (r);
 }
 
 void
diff --git a/popup.c b/popup.c
index 2146693a..6d0e1ffd 100644
--- a/popup.c
+++ b/popup.c
@@ -164,48 +164,41 @@ popup_mode_cb(__unused struct client *c, void *data, u_int *cx, u_int *cy)
 }
 
 /* Return parts of the input range which are not obstructed by the popup. */
-static void
-popup_check_cb(struct client* c, void *data, u_int px, u_int py, u_int nx,
-    struct overlay_ranges *r)
+static struct visible_ranges *
+popup_check_cb(struct client* c, void *data, u_int px, u_int py, u_int nx)
 {
 	struct popup_data	*pd = data;
-	struct overlay_ranges	 or[2];
+	struct visible_ranges	*or[2], *r;
 	u_int			 i, j, k = 0;
 
 	if (pd->md != NULL) {
 		/* Check each returned range for the menu against the popup. */
-		menu_check_cb(c, pd->md, px, py, nx, r);
-		for (i = 0; i < 2; i++) {
-			server_client_overlay_range(pd->px, pd->py, pd->sx,
-			    pd->sy, r->px[i], py, r->nx[i], &or[i]);
+		r = menu_check_cb(c, pd->md, px, py, nx);
+		for (i = 0; i < r->used; i++) {
+			or[i] = server_client_overlay_range(pd->px, pd->py, pd->sx,
+			    pd->sy, r->px[i], py, r->nx[i]);
 		}
 
 		/*
 		 * or has up to OVERLAY_MAX_RANGES non-overlapping ranges,
 		 * ordered from left to right. Collect them in the output.
 		 */
-		for (i = 0; i < 2; i++) {
-			/* Each or[i] only has 2 ranges. */
-			for (j = 0; j < 2; j++) {
-				if (or[i].nx[j] > 0) {
-					r->px[k] = or[i].px[j];
-					r->nx[k] = or[i].nx[j];
+		for (i = 0; i < r->used; i++) {
+			/* Each or[i] only has up to 2 ranges. */
+			for (j = 0; j < or[i]->used; j++) {
+				if (or[i]->nx[j] > 0) {
+					r->px[k] = or[i]->px[j];
+					r->nx[k] = or[i]->nx[j];
 					k++;
 				}
 			}
 		}
 
-		/* Zero remaining ranges if any. */
-		for (i = k; i < OVERLAY_MAX_RANGES; i++) {
-			r->px[i] = 0;
-			r->nx[i] = 0;
-		}
-
-		return;
+		return (r);
 	}
 
-	server_client_overlay_range(pd->px, pd->py, pd->sx, pd->sy, px, py, nx,
-	    r);
+	return (server_client_overlay_range(pd->px, pd->py, pd->sx, pd->sy, px, py,
+	    nx));
 }
 
 static void
diff --git a/screen-redraw.c b/screen-redraw.c
index cce06011..da3f40b5 100644
--- a/screen-redraw.c
+++ b/screen-redraw.c
@@ -817,13 +817,13 @@ screen_redraw_draw_borders_cell(struct screen_redraw_ctx *ctx, u_int i, u_int j)
 	struct window_pane	*wp, *active = server_client_get_pane(c);
 	struct grid_cell	 gc;
 	const struct grid_cell	*tmp;
-	struct overlay_ranges	 r;
+	struct visible_ranges	*r;
 	u_int			 cell_type, x = ctx->ox + i, y = ctx->oy + j;
 	int			 isolates;
 
 	if (c->overlay_check != NULL) {
-		c->overlay_check(c, c->overlay_data, x, y, 1, &r);
-		if (r.nx[0] + r.nx[1] == 0)
+		r = c->overlay_check(c, c->overlay_data, x, y, 1);
+		if (r->nx[0] + r->nx[1] == 0)
 			return;
 	}
 
@@ -943,7 +943,8 @@ screen_redraw_draw_pane(struct screen_redraw_ctx *ctx, struct window_pane *wp)
 	struct screen		*s = wp->screen;
 	struct colour_palette	*palette = &wp->palette;
 	struct grid_cell	 defaults;
-	u_int			 i, j, top, x, y, width;
+	struct visible_ranges	*vr;
+	u_int			 i, j, top, x, y, px, width, r;
 
 	if (wp->base.mode & MODE_SYNC)
 		screen_write_stop_sync(wp);
@@ -987,8 +988,23 @@ screen_redraw_draw_pane(struct screen_redraw_ctx *ctx, struct window_pane *wp)
 		log_debug("%s: %s %%%u line %u,%u at %u,%u, width %u",
 		    __func__, c->name, wp->id, i, j, x, y, width);
 
+		/* xxxx Breaking up the tty_draw_line like this isn't fully working. */
+		vr = tty_check_overlay_range(tty, x, y, width);
+
 		tty_default_colours(&defaults, wp);
-		tty_draw_line(tty, s, i, j, width, x, y, &defaults, palette);
+
+		for (r=0; r < vr->used; r++) {
+			if (vr->nx[r] == 0)
+				continue;
+			/* Convert window coordinates to tty coordinates. */
+			px = vr->px[r];
+			/* i is px of cell, add px of region, sub the
+			 * pane offset. If you don't sub offset,
+			 * contents of pane shifted. note: i apparently unnec. 
+			 */
+			tty_draw_line(tty, s, /* i + */ vr->px[r] - wp->xoff, j,
+			    vr->nx[r], px, y, &defaults, palette);
+		}
 	}
 
 #ifdef ENABLE_SIXEL
diff --git a/screen.c b/screen.c
index 7f4f9383..247d596d 100644
--- a/screen.c
+++ b/screen.c
@@ -770,3 +770,72 @@ screen_mode_to_string(int mode)
 	tmp[strlen(tmp) - 1] = '\0';
 	return (tmp);
 }
+
+#ifdef DEBUG
+/* Debug function. Usage in gdb:
+ * printf "%S",screen_print(s)
+ */
+__unused char *
+screen_print(struct screen *s) {
+	static char		 buf[16384];
+	const char		*acs;
+	u_int			 x, y;
+	size_t			 last = 0, n;
+	struct utf8_data	 ud;
+	struct grid_line	*gl;
+	struct grid_cell_entry	*gce;
+
+	for (y = 0; y < screen_hsize(s)+s->grid->sy; y++) {
+		if (last + 6 > sizeof buf) goto out;
+		n = snprintf(buf + last, sizeof buf - last, "%.4d ", y);
+		last += n;
+		buf[last++] = '"';
+		gl = &s->grid->linedata[y];
+
+		for (x = 0; x < gl->cellused; x++) {
+			gce = &gl->celldata[x];
+
+			if (gce->flags & GRID_FLAG_PADDING)
+				continue;
+
+			if (~gce->flags & GRID_FLAG_EXTENDED) {
+				/* single-byte cell stored inline */
+				if (last + 2 > sizeof buf) goto out;
+				buf[last++] = gce->data.data;
+			} else if (gce->flags & GRID_FLAG_TAB) {
+				if (last + 2 > sizeof buf) goto out;
+				buf[last++] = '\t';
+			} else if ((gce->data.data & 0xff) &&
+				  (gce->flags & GRID_ATTR_CHARSET)) {
+				/* single-byte ACS inline: try to map */
+				acs = tty_acs_get(NULL, gce->data.data);
+				if (acs != NULL) {
+					n = strlen(acs);
+					if (last + n + 1 > sizeof buf) goto out;
+					memcpy(buf + last, acs, n);
+					last += n;
+					continue;
+				}
+				buf[last++] = gce->data.data;
+			} else {
+				/* extended cell: convert utf8_char -> bytes */
+				utf8_to_data(gl->extddata[gce->offset].data,
+				    &ud);
+				if (ud.size > 0) {
+					if (last + ud.size + 1 > sizeof buf)
+						goto out;
+					memcpy(buf + last, ud.data, ud.size);
+					last += ud.size;
+				}
+			}
+		}
+
+		if (last + 3 > sizeof buf) goto out;
+		buf[last++] = '"';
+		buf[last++] = '\n';
+	}
+
+out:	buf[last] = '\0';
+	return (buf);
+}
+#endif
diff --git a/server-client.c b/server-client.c
index 1ea2fe3e..a222ac6f 100644
--- a/server-client.c
+++ b/server-client.c
@@ -165,34 +165,37 @@ server_client_clear_overlay(struct client *c)
  * Given overlay position and dimensions, return parts of the input range which
  * are visible.
  */
-void
+struct visible_ranges *
 server_client_overlay_range(u_int x, u_int y, u_int sx, u_int sy, u_int px,
-    u_int py, u_int nx, struct overlay_ranges *r)
+    u_int py, u_int nx)
 {
-	u_int	ox, onx;
+	u_int				ox, onx;
+	static struct visible_ranges	r = {NULL, NULL, 0, 0};
 
-	/* Return up to 2 ranges. */
-	r->px[2] = 0;
-	r->nx[2] = 0;
+	/* For efficiency vr is static and space reused. */
+	if (r.size == 0) {
+		r.px = xcalloc(2, sizeof(u_int));
+		r.nx = xcalloc(2, sizeof(u_int));
+		r.size = 2;
+	}
 
 	/* Trivial case of no overlap in the y direction. */
 	if (py < y || py > y + sy - 1) {
-		r->px[0] = px;
-		r->nx[0] = nx;
-		r->px[1] = 0;
-		r->nx[1] = 0;
-		return;
+		r.px[0] = px;
+		r.nx[0] = nx;
+		r.used = 1;
+		return (&r);
 	}
 
 	/* Visible bit to the left of the popup. */
 	if (px < x) {
-		r->px[0] = px;
-		r->nx[0] = x - px;
-		if (r->nx[0] > nx)
-			r->nx[0] = nx;
+		r.px[0] = px;
+		r.nx[0] = x - px;
+		if (r.nx[0] > nx)
+			r.nx[0] = nx;
 	} else {
-		r->px[0] = 0;
-		r->nx[0] = 0;
+		r.px[0] = 0;
+		r.nx[0] = 0;
 	}
 
 	/* Visible bit to the right of the popup. */
@@ -201,12 +204,14 @@ server_client_overlay_range(u_int x, u_int y, u_int sx, u_int sy, u_int px,
 		ox = px;
 	onx = px + nx;
 	if (onx > ox) {
-		r->px[1] = ox;
-		r->nx[1] = onx - ox;
+		r.px[1] = ox;
+		r.nx[1] = onx - ox;
 	} else {
-		r->px[1] = 0;
-		r->nx[1] = 0;
+		r.px[1] = 0;
+		r.nx[1] = 0;
 	}
+	r.used = 2;
+	return (&r);
 }
 
 /* Check if this client is inside this server. */
diff --git a/tmux.h b/tmux.h
index 33da541a..ec1bd543 100644
--- a/tmux.h
+++ b/tmux.h
@@ -1922,11 +1922,19 @@ struct overlay_ranges {
 	u_int	nx[OVERLAY_MAX_RANGES];
 };
 
+/* Visible range array element. */
+struct visible_ranges {
+	u_int    *px;   /* Start */
+	u_int    *nx;   /* Length */
+	size_t  used;
+	size_t  size;
+};
+
 /* Client connection. */
 typedef int (*prompt_input_cb)(struct client *, void *, const char *, int);
 typedef void (*prompt_free_cb)(void *);
-typedef void (*overlay_check_cb)(struct client*, void *, u_int, u_int, u_int,
-	    struct overlay_ranges *);
+typedef struct visible_ranges *(*overlay_check_cb)(struct client*, void *,
+	    u_int, u_int, u_int);
 typedef struct screen *(*overlay_mode_cb)(struct client *, void *, u_int *,
 	    u_int *);
 typedef void (*overlay_draw_cb)(struct client *, void *,
@@ -2551,6 +2559,8 @@ void	tty_set_path(struct tty *, const char *);
 void	tty_default_attributes(struct tty *, const struct grid_cell *,
 	    struct colour_palette *, u_int, struct hyperlinks *);
 void	tty_update_mode(struct tty *, int, struct screen *);
+struct visible_ranges *tty_check_overlay_range(struct tty *, u_int, u_int,
+	    u_int);
 
 /* tty-draw.c */
 void	tty_draw_line(struct tty *, struct screen *, u_int, u_int, u_int,
@@ -2567,6 +2577,7 @@ void	tty_close(struct tty *);
 void	tty_free(struct tty *);
 void	tty_update_features(struct tty *);
 void	tty_set_selection(struct tty *, const char *, const char *, size_t);
+u_int	tty_cell_width(const struct grid_cell *, u_int);
 void	tty_write(void (*)(struct tty *, const struct tty_ctx *),
 	    struct tty_ctx *);
 void	tty_cmd_alignmenttest(struct tty *, const struct tty_ctx *);
@@ -2909,8 +2920,8 @@ void	 server_client_set_overlay(struct client *, u_int, overlay_check_cb,
 	     overlay_mode_cb, overlay_draw_cb, overlay_key_cb,
 	     overlay_free_cb, overlay_resize_cb, void *);
 void	 server_client_clear_overlay(struct client *);
-void	 server_client_overlay_range(u_int, u_int, u_int, u_int, u_int, u_int,
-	     u_int, struct overlay_ranges *);
+struct visible_ranges	*server_client_overlay_range(u_int, u_int, u_int, u_int, u_int, u_int,
+	     u_int);
 void	 server_client_set_key_table(struct client *, const char *);
 const char *server_client_get_key_table(struct client *);
 int	 server_client_check_nested(struct client *);
@@ -3231,6 +3242,7 @@ void	 screen_select_cell(struct screen *, struct grid_cell *,
 void	 screen_alternate_on(struct screen *, struct grid_cell *, int);
 void	 screen_alternate_off(struct screen *, struct grid_cell *, int);
 const char *screen_mode_to_string(int);
+__unused char * screen_print(struct screen *s);
 
 /* window.c */
 extern struct windows windows;
@@ -3611,8 +3623,7 @@ int		 menu_display(struct menu *, int, int, struct cmdq_item *,
 		    const char *, const char *, struct cmd_find_state *,
 		    menu_choice_cb, void *);
 struct screen	*menu_mode_cb(struct client *, void *, u_int *, u_int *);
-void		 menu_check_cb(struct client *, void *, u_int, u_int, u_int,
-		    struct overlay_ranges *);
+struct visible_ranges	*menu_check_cb(struct client *, void *, u_int, u_int, u_int);
 void		 menu_draw_cb(struct client *, void *,
 		    struct screen_redraw_ctx *);
 void		 menu_free_cb(struct client *, void *);
diff --git a/tty.c b/tty.c
index bc1df836..5ff225d6 100644
--- a/tty.c
+++ b/tty.c
@@ -66,8 +66,7 @@ static void	tty_emulate_repeat(struct tty *, enum tty_code_code,
 		    enum tty_code_code, u_int);
 static void	tty_draw_pane(struct tty *, const struct tty_ctx *, u_int);
 static int	tty_check_overlay(struct tty *, u_int, u_int);
-static void	tty_check_overlay_range(struct tty *, u_int, u_int, u_int,
-		    struct overlay_ranges *);
+struct visible_ranges *tty_check_overlay_range(struct tty *, u_int, u_int, u_int);
 
 #ifdef ENABLE_SIXEL
 static void	tty_write_one(void (*)(struct tty *, const struct tty_ctx *),
@@ -1161,7 +1160,7 @@ tty_clear_line(struct tty *tty, const struct grid_cell *defaults, u_int py,
     u_int px, u_int nx, u_int bg)
 {
 	struct client		*c = tty->client;
-	struct overlay_ranges	 r;
+	struct visible_ranges	*r;
 	u_int			 i;
 
 	log_debug("%s: %s, %u at %u,%u", __func__, c->name, nx, px, py);
@@ -1198,13 +1197,17 @@ tty_clear_line(struct tty *tty, const struct grid_cell *defaults, u_int py,
 	 * Couldn't use an escape sequence, use spaces. Clear only the visible
 	 * bit if there is an overlay.
 	 */
-	tty_check_overlay_range(tty, px, py, nx, &r);
-	for (i = 0; i < OVERLAY_MAX_RANGES; i++) {
-		if (r.nx[i] == 0)
+	tty_cursor(tty, px, py);
+	tty_repeat_space(tty, nx);
+	/*
+	r = tty_check_overlay_range(tty, px, py, nx);
+	for (i = 0; i < r->used; i++) {
+		if (r->nx[i] == 0)
 			continue;
-		tty_cursor(tty, r.px[i], py);
-		tty_repeat_space(tty, r.nx[i]);
+		tty_cursor(tty, r->px[i], py);
+		tty_repeat_space(tty, r->nx[i]);
 	}
+	*/
 }
 
 /* Clear a line, adjusting to visible part of pane. */
@@ -1418,6 +1421,20 @@ tty_check_codeset(struct tty *tty, const struct grid_cell *gc)
 	return (&new);
 }
 
+/*
+ * Compute the effective display width (in terminal columns) of a grid cell
+ * when it will be drawn at terminal column atcol.
+ */
+u_int
+tty_cell_width(const struct grid_cell *gcp, u_int atcol)
+{
+	/* Tabs expand to the next tab stop (tab width = 8). */
+	if (gcp->flags & GRID_FLAG_TAB)
+		return (8 - (atcol % 8));
+	/* Normal characters: width stored in cell (1 or 2 usually). */
+	return (gcp->data.width);
+}
+
 /*
  * Check if a single character is obstructed by the overlay and return a
  * boolean.
@@ -1425,37 +1442,41 @@ tty_check_codeset(struct tty *tty, const struct grid_cell *gc)
 static int
 tty_check_overlay(struct tty *tty, u_int px, u_int py)
 {
-	struct overlay_ranges	r;
+	struct visible_ranges *r;
 
 	/*
 	 * A unit width range will always return nx[2] == 0 from a check, even
 	 * with multiple overlays, so it's sufficient to check just the first
 	 * two entries.
 	 */
-	tty_check_overlay_range(tty, px, py, 1, &r);
-	if (r.nx[0] + r.nx[1] == 0)
+	r = tty_check_overlay_range(tty, px, py, 1);
+	if (r->nx[0] + r->nx[1] == 0)
 		return (0);
 	return (1);
 }
 
 /* Return parts of the input range which are visible. */
-static void
-tty_check_overlay_range(struct tty *tty, u_int px, u_int py, u_int nx,
-    struct overlay_ranges *r)
+struct visible_ranges *
+tty_check_overlay_range(struct tty *tty, u_int px, u_int py, u_int nx)
 {
+	static struct visible_ranges r = {NULL, NULL, 0, 0};
 	struct client	*c = tty->client;
 
-	if (c->overlay_check == NULL) {
-		r->px[0] = px;
-		r->nx[0] = nx;
-		r->px[1] = 0;
-		r->nx[1] = 0;
-		r->px[2] = 0;
-		r->nx[2] = 0;
-		return;
+	/* For efficiency vr is static and space reused. */
+	if (r.size == 0) {
+		r.px = xcalloc(1, sizeof(u_int));
+		r.nx = xcalloc(1, sizeof(u_int));
+		r.size = 1;
 	}
 
-	c->overlay_check(c, c->overlay_data, px, py, nx, r);
+	if (c->overlay_check == NULL) {
+		r.px[0] = px;
+		r.nx[0] = nx;
+		r.used = 1;
+		return (&r);
+	}
+
+	return (c->overlay_check(c, c->overlay_data, px, py, nx));
 }
 
 #ifdef ENABLE_SIXEL
@@ -1983,7 +2004,7 @@ tty_cmd_cell(struct tty *tty, const struct tty_ctx *ctx)
 {
 	const struct grid_cell	*gcp = ctx->cell;
 	struct screen		*s = ctx->s;
-	struct overlay_ranges	 r;
+	struct visible_ranges	*r;
 	u_int			 px, py, i, vis = 0;
 
 	px = ctx->xoff + ctx->ocx - ctx->wox;
@@ -2000,9 +2021,9 @@ tty_cmd_cell(struct tty *tty, const struct tty_ctx *ctx)
 
 	/* Handle partially obstructed wide characters. */
 	if (gcp->data.width > 1) {
-		tty_check_overlay_range(tty, px, py, gcp->data.width, &r);
-		for (i = 0; i < OVERLAY_MAX_RANGES; i++)
-			vis += r.nx[i];
+		r = tty_check_overlay_range(tty, px, py, gcp->data.width);
+		for (i = 0; i < r->used; i++)
+			vis += r->nx[i];
 		if (vis < gcp->data.width) {
 			tty_draw_line(tty, s, s->cx, s->cy, gcp->data.width,
 			    px, py, &ctx->defaults, ctx->palette);
@@ -2028,7 +2049,7 @@ tty_cmd_cell(struct tty *tty, const struct tty_ctx *ctx)
 void
 tty_cmd_cells(struct tty *tty, const struct tty_ctx *ctx)
 {
-	struct overlay_ranges	 r;
+	struct visible_ranges	*r;
 	u_int			 i, px, py, cx;
 	char			*cp = ctx->ptr;
 
@@ -2059,14 +2080,14 @@ tty_cmd_cells(struct tty *tty, const struct tty_ctx *ctx)
 	px = ctx->xoff + ctx->ocx - ctx->wox;
 	py = ctx->yoff + ctx->ocy - ctx->woy;
 
-	tty_check_overlay_range(tty, px, py, ctx->num, &r);
-	for (i = 0; i < OVERLAY_MAX_RANGES; i++) {
-		if (r.nx[i] == 0)
+	r = tty_check_overlay_range(tty, px, py, ctx->num);
+	for (i = 0; i < r->used; i++) {
+		if (r->nx[i] == 0)
 			continue;
 		/* Convert back to pane position for printing. */
-		cx = r.px[i] - ctx->xoff + ctx->wox;
+		cx = r->px[i] - ctx->xoff + ctx->wox;
 		tty_cursor_pane_unless_wrap(tty, ctx, cx, ctx->ocy);
-		tty_putn(tty, cp + r.px[i] - px, r.nx[i], r.nx[i]);
+		tty_putn(tty, cp + r->px[i] - px, r->nx[i], r->nx[i]);
 	}
 }