diff --git a/popup.c b/popup.c
index 2092e185..cb8dbf06 100644
--- a/popup.c
+++ b/popup.c
@@ -185,7 +185,6 @@ popup_set_client_cb(struct tty_ctx *ttyctx, struct client *c)
 	if (pd->c->flags & CLIENT_REDRAWOVERLAY)
 		return (0);
 
-	ttyctx->bigger = 0;
 	ttyctx->wox = 0;
 	ttyctx->woy = 0;
 	ttyctx->wsx = c->tty.sx;
@@ -208,6 +207,7 @@ popup_init_ctx_cb(struct screen_write_ctx *ctx, struct tty_ctx *ttyctx)
 	struct popup_data	*pd = ctx->arg;
 
 	memcpy(&ttyctx->defaults, &pd->defaults, sizeof ttyctx->defaults);
+	ttyctx->flags &= ~TTY_CTX_WINDOW_BIGGER;
 	ttyctx->palette = &pd->palette;
 	ttyctx->redraw_cb = popup_redraw_cb;
 	ttyctx->set_client_cb = popup_set_client_cb;
diff --git a/screen-write.c b/screen-write.c
index 30f73d86..e6cc0d59 100644
--- a/screen-write.c
+++ b/screen-write.c
@@ -133,7 +133,7 @@ screen_write_set_client_cb(struct tty_ctx *ttyctx, struct client *c)
 {
 	struct window_pane	*wp = ttyctx->arg;
 
-	if (ttyctx->allow_invisible_panes) {
+	if (ttyctx->flags & TTY_CTX_INVISIBLE_PANES) {
 		if (session_has(c->session, wp->window))
 			return (1);
 		return (0);
@@ -157,8 +157,11 @@ screen_write_set_client_cb(struct tty_ctx *ttyctx, struct client *c)
 		return (-1);
 	}
 
-	ttyctx->bigger = tty_window_offset(&c->tty, &ttyctx->wox, &ttyctx->woy,
-	    &ttyctx->wsx, &ttyctx->wsy);
+	if (tty_window_offset(&c->tty, &ttyctx->wox, &ttyctx->woy, &ttyctx->wsx,
+	    &ttyctx->wsy))
+		ttyctx->flags |= TTY_CTX_WINDOW_BIGGER;
+	else
+		ttyctx->flags &= ~TTY_CTX_WINDOW_BIGGER;
 
 	ttyctx->xoff = ttyctx->rxoff = wp->xoff;
 	ttyctx->yoff = ttyctx->ryoff = wp->yoff;
@@ -213,13 +216,14 @@ screen_write_initctx(struct screen_write_ctx *ctx, struct tty_ctx *ttyctx,
 		 * move the cursor); for other panes, always use it, since the
 		 * cursor will have to move.
 		 */
-		if (ctx->wp != NULL) {
-			if (ctx->wp != ctx->wp->window->active)
-				ttyctx->num = 1;
-			else
-				ttyctx->num = sync;
-		} else
-			ttyctx->num = 0x10|sync;
+		if (ctx->wp != NULL && ctx->wp != ctx->wp->window->active)
+			ttyctx->flags |= TTY_CTX_SYNC;
+		else {
+			if (ctx->wp == NULL)
+				ttyctx->flags |= TTY_CTX_OVERLAY_SYNC;
+			if (sync)
+				ttyctx->flags |= TTY_CTX_SYNC;
+		}
 		tty_write(tty_cmd_syncstart, ttyctx);
 		ctx->flags |= SCREEN_WRITE_SYNC;
 	}
@@ -572,6 +576,7 @@ screen_write_fast_copy(struct screen_write_ctx *ctx, struct screen *src,
 	struct window_pane	*wp = ctx->wp;
 	struct tty_ctx	 	 ttyctx;
 	struct grid		*gd = src->grid;
+	struct grid_line	*gl, *sgl;
 	struct grid_cell	 gc;
 	u_int		 	 xx, yy, cx = s->cx, cy = s->cy;
 
@@ -585,18 +590,22 @@ screen_write_fast_copy(struct screen_write_ctx *ctx, struct screen *src,
 		if (wp != NULL)
 			screen_write_initctx(ctx, &ttyctx, 0);
 		for (xx = px; xx < px + nx; xx++) {
-			if (xx >= grid_get_line(gd, yy)->cellsize &&
-			    s->cx >= grid_get_line(ctx->s->grid, s->cy)->cellsize)
+			gl = grid_get_line(gd, yy);
+			sgl = grid_get_line(ctx->s->grid, s->cy);
+			if (xx >= gl->cellsize && s->cx >= sgl->cellsize)
 				break;
 			grid_get_cell(gd, xx, yy, &gc);
 			if (xx + gc.data.width > px + nx)
 				break;
 			grid_view_set_cell(ctx->s->grid, s->cx, s->cy, &gc);
-			if (wp != NULL) {
-				ttyctx.cell = &gc;
-				tty_write(tty_cmd_cell, &ttyctx);
-				ttyctx.ocx++;
+			if (wp == NULL) {
+				s->cx++;
+				continue;
 			}
+			ttyctx.cell = &gc;
+			ttyctx.flags &= (TTY_CTX_OVERLAY_SYNC|TTY_CTX_SYNC);
+			tty_write(tty_cmd_cell, &ttyctx);
+			ttyctx.ocx++;
 			s->cx++;
 		}
 		s->cy++;
@@ -1871,7 +1880,8 @@ screen_write_collect_flush(struct screen_write_ctx *ctx, int scroll_only,
 			} else {
 				screen_write_initctx(ctx, &ttyctx, 0);
 				ttyctx.cell = &ci->gc;
-				ttyctx.wrapped = ci->wrapped;
+				if (ci->wrapped)
+					ttyctx.flags |= TTY_CTX_WRAPPED;
 				ttyctx.ptr = cl->data + ci->x;
 				ttyctx.num = ci->used;
 				tty_write(tty_cmd_cells, &ttyctx);
@@ -2177,7 +2187,8 @@ screen_write_cell(struct screen_write_ctx *ctx, const struct grid_cell *gc)
 			ttyctx.cell = &tmp_gc;
 		} else
 			ttyctx.cell = gc;
-		ttyctx.num = redraw ? 2 : 0;
+		if (redraw)
+			ttyctx.flags |= TTY_CTX_CELL_DRAW_LINE;
 		tty_write(tty_cmd_cell, &ttyctx);
 	}
 }
@@ -2245,7 +2256,7 @@ screen_write_combine(struct screen_write_ctx *ctx, const struct grid_cell *gc)
 			if (utf8_should_combine(&last.data, ud))
 				force_wide = 1;
 			else if (utf8_should_combine(ud, &last.data))
-                               force_wide = 1;
+				force_wide = 1;
 			else if (!utf8_has_zwj(&last.data))
 				return (0);
 			break;
@@ -2289,7 +2300,8 @@ screen_write_combine(struct screen_write_ctx *ctx, const struct grid_cell *gc)
 	screen_write_set_cursor(ctx, cx - n, cy);
 	screen_write_initctx(ctx, &ttyctx, 0);
 	ttyctx.cell = &last;
-	ttyctx.num = force_wide; /* reset cached cursor position */
+	if (force_wide)
+		ttyctx.flags |= TTY_CTX_CELL_INVALIDATE;
 	tty_write(tty_cmd_cell, &ttyctx);
 	screen_write_set_cursor(ctx, cx, cy);
 
@@ -2391,9 +2403,10 @@ screen_write_rawstring(struct screen_write_ctx *ctx, u_char *str, u_int len,
 	struct tty_ctx	ttyctx;
 
 	screen_write_initctx(ctx, &ttyctx, 0);
+	if (allow_invisible_panes)
+		ttyctx.flags |= TTY_CTX_INVISIBLE_PANES;
 	ttyctx.ptr = str;
 	ttyctx.num = len;
-	ttyctx.allow_invisible_panes = allow_invisible_panes;
 
 	tty_write(tty_cmd_rawstring, &ttyctx);
 }
diff --git a/tmux.h b/tmux.h
index 0b2afbe9..47228afb 100644
--- a/tmux.h
+++ b/tmux.h
@@ -1732,18 +1732,18 @@ struct tty_ctx {
 	void			*arg;
 
 	const struct grid_cell	*cell;
-	int			 wrapped;
+	int                      flags;
+#define TTY_CTX_WRAPPED 0x1
+#define TTY_CTX_INVISIBLE_PANES 0x2
+#define TTY_CTX_WINDOW_BIGGER 0x4
+#define TTY_CTX_SYNC 0x8
+#define TTY_CTX_OVERLAY_SYNC 0x10
+#define TTY_CTX_CELL_DRAW_LINE 0x20
+#define TTY_CTX_CELL_INVALIDATE 0x40
 
-	u_int			 num;
-	void			*ptr;
-	void			*ptr2;
-
-	/*
-	 * Whether this command should be sent even when the pane is not
-	 * visible (used for a passthrough sequence when allow-passthrough is
-	 * "all").
-	 */
-	int			 allow_invisible_panes;
+	u_int		 num;
+	void		*ptr;
+	void		*ptr2;
 
 	/*
 	 * Cursor and region position before the screen was updated - this is
@@ -1772,7 +1772,6 @@ struct tty_ctx {
 	struct colour_palette	*palette;
 
 	/* Containing region (usually window) offset and size. */
-	int			 bigger;
 	u_int			 wox;
 	u_int			 woy;
 	u_int			 wsx;
diff --git a/tty.c b/tty.c
index 1fdd5c2f..fd22df11 100644
--- a/tty.c
+++ b/tty.c
@@ -1109,7 +1109,7 @@ tty_is_visible(__unused struct tty *tty, const struct tty_ctx *ctx, u_int px,
 {
 	u_int	xoff = ctx->rxoff + px, yoff = ctx->ryoff + py;
 
-	if (!ctx->bigger)
+	if (~ctx->flags & TTY_CTX_WINDOW_BIGGER)
 		return (1);
 
 	if (xoff + nx <= ctx->wox || xoff >= ctx->wox + ctx->wsx ||
@@ -1377,9 +1377,9 @@ tty_draw_pane(struct tty *tty, const struct tty_ctx *ctx, u_int py)
 	struct visible_ranges	*r;
 	struct visible_range	*rr;
 
-	log_debug("%s: %s %u %d", __func__, tty->client->name, py, ctx->bigger);
+	log_debug("%s: %s %u", __func__, tty->client->name, py);
 
-	if (!ctx->bigger) {
+	if (~ctx->flags & TTY_CTX_WINDOW_BIGGER) {
 		r = tty_check_overlay_range(tty, ctx->xoff, ctx->yoff + py, nx);
 		for (j = 0; j < r->used; j++) {
 			rr = &r->ranges[j];
@@ -1561,7 +1561,7 @@ tty_client_ready(const struct tty_ctx *ctx, struct client *c)
 	 * If invisible panes are allowed (used for passthrough), don't care if
 	 * redrawing or frozen.
 	 */
-	if (ctx->allow_invisible_panes)
+	if (ctx->flags & TTY_CTX_INVISIBLE_PANES)
 		return (1);
 
 	if (c->flags & CLIENT_REDRAWWINDOW)
@@ -1610,7 +1610,7 @@ tty_cmd_insertcharacter(struct tty *tty, const struct tty_ctx *ctx)
 {
 	struct client	*c = tty->client;
 
-	if (ctx->bigger ||
+	if ((ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
 	    !tty_full_width(tty, ctx) ||
 	    tty_fake_bce(tty, &ctx->defaults, ctx->bg) ||
 	    (!tty_term_has(tty->term, TTYC_ICH) &&
@@ -1633,7 +1633,7 @@ tty_cmd_deletecharacter(struct tty *tty, const struct tty_ctx *ctx)
 {
 	struct client	*c = tty->client;
 
-	if (ctx->bigger ||
+	if ((ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
 	    !tty_full_width(tty, ctx) ||
 	    tty_fake_bce(tty, &ctx->defaults, ctx->bg) ||
 	    (!tty_term_has(tty->term, TTYC_DCH) &&
@@ -1665,7 +1665,7 @@ tty_cmd_insertline(struct tty *tty, const struct tty_ctx *ctx)
 {
 	struct client	*c = tty->client;
 
-	if (ctx->bigger ||
+	if ((ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
 	    !tty_full_width(tty, ctx) ||
 	    tty_fake_bce(tty, &ctx->defaults, ctx->bg) ||
 	    !tty_term_has(tty->term, TTYC_CSR) ||
@@ -1693,7 +1693,7 @@ tty_cmd_deleteline(struct tty *tty, const struct tty_ctx *ctx)
 {
 	struct client	*c = tty->client;
 
-	if (ctx->bigger ||
+	if ((ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
 	    !tty_full_width(tty, ctx) ||
 	    tty_fake_bce(tty, &ctx->defaults, ctx->bg) ||
 	    !tty_term_has(tty->term, TTYC_CSR) ||
@@ -1753,7 +1753,7 @@ tty_cmd_reverseindex(struct tty *tty, const struct tty_ctx *ctx)
 	if (ctx->ocy != ctx->orupper)
 		return;
 
-	if (ctx->bigger ||
+	if ((ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
 	    (!tty_full_width(tty, ctx) && !tty_use_margin(tty)) ||
 	    tty_fake_bce(tty, &ctx->defaults, 8) ||
 	    !tty_term_has(tty->term, TTYC_CSR) ||
@@ -1787,7 +1787,7 @@ tty_cmd_linefeed(struct tty *tty, const struct tty_ctx *ctx)
 	if (ctx->ocy != ctx->orlower)
 		return;
 
-	if (ctx->bigger ||
+	if ((ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
 	    (!tty_full_width(tty, ctx) && !tty_use_margin(tty)) ||
 	    tty_fake_bce(tty, &ctx->defaults, 8) ||
 	    !tty_term_has(tty->term, TTYC_CSR) ||
@@ -1828,7 +1828,7 @@ tty_cmd_scrollup(struct tty *tty, const struct tty_ctx *ctx)
 	struct client	*c = tty->client;
 	u_int		 i;
 
-	if (ctx->bigger ||
+	if ((ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
 	    (!tty_full_width(tty, ctx) && !tty_use_margin(tty)) ||
 	    tty_fake_bce(tty, &ctx->defaults, 8) ||
 	    !tty_term_has(tty->term, TTYC_CSR) ||
@@ -1867,7 +1867,7 @@ tty_cmd_scrolldown(struct tty *tty, const struct tty_ctx *ctx)
 	u_int		 i;
 	struct client	*c = tty->client;
 
-	if (ctx->bigger ||
+	if ((ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
 	    (!tty_full_width(tty, ctx) && !tty_use_margin(tty)) ||
 	    tty_fake_bce(tty, &ctx->defaults, 8) ||
 	    !tty_term_has(tty->term, TTYC_CSR) ||
@@ -1969,7 +1969,7 @@ tty_cmd_alignmenttest(struct tty *tty, const struct tty_ctx *ctx)
 {
 	u_int	i, j;
 
-	if (ctx->bigger) {
+	if (ctx->flags & TTY_CTX_WINDOW_BIGGER) {
 		ctx->redraw_cb(ctx);
 		return;
 	}
@@ -2001,7 +2001,7 @@ tty_cmd_cell(struct tty *tty, const struct tty_ctx *ctx)
 	    (gcp->data.width == 1 && !tty_check_overlay(tty, px, py)))
 		return;
 
-	if (ctx->num == 2) {
+	if (ctx->flags & TTY_CTX_CELL_DRAW_LINE) {
 		tty_draw_line(tty, s, 0, s->cy, screen_size_x(s),
 		    ctx->xoff - ctx->wox, py, &ctx->defaults, ctx->palette);
 		return;
@@ -2030,7 +2030,7 @@ tty_cmd_cell(struct tty *tty, const struct tty_ctx *ctx)
 	tty_cell(tty, ctx->cell, &ctx->defaults, ctx->palette,
 	    ctx->s->hyperlinks);
 
-	if (ctx->num == 1)
+	if (ctx->flags & TTY_CTX_CELL_INVALIDATE)
 		tty_invalidate(tty);
 }
 
@@ -2045,10 +2045,10 @@ tty_cmd_cells(struct tty *tty, const struct tty_ctx *ctx)
 	if (!tty_is_visible(tty, ctx, ctx->ocx, ctx->ocy, ctx->num, 1))
 		return;
 
-	if (ctx->bigger &&
+	if ((ctx->flags & TTY_CTX_WINDOW_BIGGER) &&
 	    (ctx->xoff + ctx->ocx < ctx->wox ||
 	    ctx->xoff + ctx->ocx + ctx->num > ctx->wox + ctx->wsx)) {
-		if (!ctx->wrapped ||
+		if ((~ctx->flags & TTY_CTX_WRAPPED) ||
 		    !tty_full_width(tty, ctx) ||
 		    (tty->term->flags & TERM_NOAM) ||
 		    ctx->xoff + ctx->ocx != 0 ||
@@ -2172,20 +2172,23 @@ tty_cmd_sixelimage(struct tty *tty, const struct tty_ctx *ctx)
 void
 tty_cmd_syncstart(struct tty *tty, const struct tty_ctx *ctx)
 {
-	if (ctx->num == 0x11) {
-		/*
-		 * This is an overlay and a command that moves the cursor so
-		 * start synchronized updates.
-		 */
-		tty_sync_start(tty);
-	} else if (~ctx->num & 0x10) {
-		/*
-		 * This is a pane. If there is an overlay, always start;
-		 * otherwise, only if requested.
-		 */
-		if (ctx->num || tty->client->overlay_draw != NULL)
-			tty_sync_start(tty);
-	}
+	struct client	*c = tty->client;
+
+        if ((ctx->flags & TTY_CTX_OVERLAY_SYNC) &&
+            (ctx->flags & TTY_CTX_SYNC)) {
+                /*
+                 * This is an overlay and a command that moves the cursor so
+                 * start synchronized updates.
+                 */
+                tty_sync_start(tty);
+        } else if (~ctx->flags & TTY_CTX_OVERLAY_SYNC) {
+                /*
+                 * This is a pane. If there is an overlay, always start;
+                 * otherwise, only if requested.
+                 */
+                if ((ctx->flags & TTY_CTX_SYNC) || c->overlay_draw != NULL)
+                        tty_sync_start(tty);
+        }
 }
 
 void
@@ -2351,7 +2354,7 @@ static void
 tty_cursor_pane_unless_wrap(struct tty *tty, const struct tty_ctx *ctx,
     u_int cx, u_int cy)
 {
-	if (!ctx->wrapped ||
+	if ((~ctx->flags & TTY_CTX_WRAPPED) ||
 	    !tty_full_width(tty, ctx) ||
 	    (tty->term->flags & TERM_NOAM) ||
 	    ctx->xoff + cx != 0 ||