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 21e7b7cb..bfeec9c8 100644
--- a/screen-write.c
+++ b/screen-write.c
@@ -36,7 +36,6 @@ static int	screen_write_overwrite(struct screen_write_ctx *,
 		    struct grid_cell *, u_int);
 static int	screen_write_combine(struct screen_write_ctx *,
 		    const struct grid_cell *);
-static int	screen_write_pane_obscured(struct window_pane *);
 
 struct screen_write_citem {
 	u_int				x;
@@ -134,7 +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);
@@ -158,8 +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;
@@ -170,10 +172,43 @@ screen_write_set_client_cb(struct tty_ctx *ttyctx, struct client *c)
 	return (1);
 }
 
+/* Return 1 if there is a floating window pane overlapping this pane. */
+static int
+screen_write_pane_is_obscured(struct screen_write_ctx *ctx)
+{
+        struct window_pane	*wp = ctx->wp;
+
+        if (ctx->wp == NULL)
+                return (0);
+
+	if (ctx->flags & SCREEN_WRITE_CHECKED_IF_OBSCURED) {
+		if (ctx->flags & SCREEN_WRITE_OBSCURED)
+			return (1);
+		return (0);
+	}
+	ctx->flags |= SCREEN_WRITE_CHECKED_IF_OBSCURED;
+
+        while ((wp = TAILQ_PREV(wp, window_panes, zentry)) != NULL) {
+                if ((wp->flags & PANE_FLOATING) &&
+                    ((wp->yoff >= ctx->wp->yoff &&
+                    wp->yoff <= ctx->wp->yoff + (int)ctx->wp->sy) ||
+                    (wp->yoff + (int)wp->sy >= ctx->wp->yoff &&
+                    wp->yoff + wp->sy <= ctx->wp->yoff + ctx->wp->sy)) &&
+                    ((wp->xoff >= ctx->wp->xoff &&
+                    wp->xoff <= ctx->wp->xoff + (int)ctx->wp->sx) ||
+                    (wp->xoff + (int)wp->sx >= ctx->wp->xoff &&
+                    wp->xoff + wp->sx <= ctx->wp->xoff + ctx->wp->sx))) {
+			ctx->flags |= SCREEN_WRITE_OBSCURED;
+                        return (1);
+		}
+        }
+        return (0);
+}
+
 /* Set up context for TTY command. */
 static void
 screen_write_initctx(struct screen_write_ctx *ctx, struct tty_ctx *ttyctx,
-    int sync)
+    int is_sync, int check_obscured)
 {
 	struct screen	*s = ctx->s;
 
@@ -188,6 +223,9 @@ screen_write_initctx(struct screen_write_ctx *ctx, struct tty_ctx *ttyctx,
 	ttyctx->orlower = s->rlower;
 	ttyctx->orupper = s->rupper;
 
+	if (check_obscured && screen_write_pane_is_obscured(ctx))
+		ttyctx->flags |= TTY_CTX_PANE_OBSCURED;
+
 	memcpy(&ttyctx->defaults, &grid_default_cell, sizeof ttyctx->defaults);
 	if (ctx->init_ctx_cb != NULL) {
 		ctx->init_ctx_cb(ctx, ttyctx);
@@ -214,13 +252,14 @@ 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 (is_sync)
+				ttyctx->flags |= TTY_CTX_SYNC;
+		}
 		tty_write(tty_cmd_syncstart, ttyctx);
 		ctx->flags |= SCREEN_WRITE_SYNC;
 	}
@@ -573,6 +612,7 @@ 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;
 	int			 yoff = 0;
@@ -585,28 +625,26 @@ screen_write_fast_copy(struct screen_write_ctx *ctx, struct screen *src,
 		if (yy >= gd->hsize + gd->sy)
 			break;
 		s->cx = cx;
-		screen_write_initctx(ctx, &ttyctx, 0);
-		if (wp != NULL) {
+		screen_write_initctx(ctx, &ttyctx, 0, 0);
+		if (wp != NULL)
 			yoff = wp->yoff;
-		}
 		r = screen_redraw_get_visible_ranges(wp, px, s->cy + yoff, nx,
 		    NULL);
 		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) {
-				if (! screen_redraw_is_visible(r, px))
-					break;
-				ttyctx.cell = &gc;
-				tty_write(tty_cmd_cell, &ttyctx);
-				ttyctx.ocx++;
-			}
+			if (!screen_redraw_is_visible(r, px))
+				break;
+			ttyctx.cell = &gc;
+			ttyctx.flags &= (TTY_CTX_OVERLAY_SYNC|TTY_CTX_SYNC);
+			tty_write(tty_cmd_cell, &ttyctx);
+			ttyctx.ocx++;
 			s->cx++;
 		}
 		s->cy++;
@@ -1097,7 +1135,7 @@ screen_write_alignmenttest(struct screen_write_ctx *ctx)
 	s->rupper = 0;
 	s->rlower = screen_size_y(s) - 1;
 
-	screen_write_initctx(ctx, &ttyctx, 1);
+	screen_write_initctx(ctx, &ttyctx, 1, 1);
 
 	screen_write_collect_clear(ctx, 0, screen_size_y(s) - 1);
 	tty_write(tty_cmd_alignmenttest, &ttyctx);
@@ -1126,9 +1164,8 @@ screen_write_insertcharacter(struct screen_write_ctx *ctx, u_int nx, u_int bg)
 		ctx->wp->flags |= PANE_REDRAW;
 #endif
 
-	screen_write_initctx(ctx, &ttyctx, 0);
+	screen_write_initctx(ctx, &ttyctx, 0, 1);
 	ttyctx.bg = bg;
-	ttyctx.obscured = screen_write_pane_obscured(ctx->wp);
 
 	grid_view_insert_cells(s->grid, s->cx, s->cy, nx, bg);
 
@@ -1160,9 +1197,8 @@ screen_write_deletecharacter(struct screen_write_ctx *ctx, u_int nx, u_int bg)
 		ctx->wp->flags |= PANE_REDRAW;
 #endif
 
-	screen_write_initctx(ctx, &ttyctx, 0);
+	screen_write_initctx(ctx, &ttyctx, 0, 1);
 	ttyctx.bg = bg;
-	ttyctx.obscured = screen_write_pane_obscured(ctx->wp);
 
 	grid_view_delete_cells(s->grid, s->cx, s->cy, nx, bg);
 
@@ -1194,7 +1230,7 @@ screen_write_clearcharacter(struct screen_write_ctx *ctx, u_int nx, u_int bg)
 		ctx->wp->flags |= PANE_REDRAW;
 #endif
 
-	screen_write_initctx(ctx, &ttyctx, 0);
+	screen_write_initctx(ctx, &ttyctx, 0, 0);
 	ttyctx.bg = bg;
 
 	grid_view_clear(s->grid, s->cx, s->cy, nx, 1, bg);
@@ -1230,9 +1266,8 @@ screen_write_insertline(struct screen_write_ctx *ctx, u_int ny, u_int bg)
 		if (ny == 0)
 			return;
 
-		screen_write_initctx(ctx, &ttyctx, 1);
+		screen_write_initctx(ctx, &ttyctx, 1, 1);
 		ttyctx.bg = bg;
-		ttyctx.obscured = screen_write_pane_obscured(ctx->wp);
 
 		grid_view_insert_lines(gd, s->cy, ny, bg);
 
@@ -1247,11 +1282,8 @@ screen_write_insertline(struct screen_write_ctx *ctx, u_int ny, u_int bg)
 	if (ny == 0)
 		return;
 
-	screen_write_initctx(ctx, &ttyctx, 1);
+	screen_write_initctx(ctx, &ttyctx, 1, 1);
 	ttyctx.bg = bg;
-	ttyctx.obscured = screen_write_pane_obscured(ctx->wp);
-	log_debug("%s: obscured=%d for pane %%%u", __func__,
-	    ttyctx.obscured, ctx->wp != NULL ? ctx->wp->id : 0);
 
 	if (s->cy < s->rupper || s->cy > s->rlower)
 		grid_view_insert_lines(gd, s->cy, ny, bg);
@@ -1287,9 +1319,8 @@ screen_write_deleteline(struct screen_write_ctx *ctx, u_int ny, u_int bg)
 		if (ny == 0)
 			return;
 
-		screen_write_initctx(ctx, &ttyctx, 1);
+		screen_write_initctx(ctx, &ttyctx, 1, 1);
 		ttyctx.bg = bg;
-		ttyctx.obscured = screen_write_pane_obscured(ctx->wp);
 
 		grid_view_delete_lines(gd, s->cy, ny, bg);
 
@@ -1304,11 +1335,8 @@ screen_write_deleteline(struct screen_write_ctx *ctx, u_int ny, u_int bg)
 	if (ny == 0)
 		return;
 
-	screen_write_initctx(ctx, &ttyctx, 1);
+	screen_write_initctx(ctx, &ttyctx, 1, 1);
 	ttyctx.bg = bg;
-	ttyctx.obscured = screen_write_pane_obscured(ctx->wp);
-	log_debug("%s: obscured=%d for pane %%%u", __func__,
-	    ttyctx.obscured, ctx->wp != NULL ? ctx->wp->id : 0);
 
 	if (s->cy < s->rupper || s->cy > s->rlower)
 		grid_view_delete_lines(gd, s->cy, ny, bg);
@@ -1467,7 +1495,7 @@ screen_write_reverseindex(struct screen_write_ctx *ctx, u_int bg)
 		grid_view_scroll_region_down(s->grid, s->rupper, s->rlower, bg);
 		screen_write_collect_flush(ctx, 0, __func__);
 
-		screen_write_initctx(ctx, &ttyctx, 1);
+		screen_write_initctx(ctx, &ttyctx, 1, 0);
 		ttyctx.bg = bg;
 
 		tty_write(tty_cmd_reverseindex, &ttyctx);
@@ -1578,9 +1606,8 @@ screen_write_scrolldown(struct screen_write_ctx *ctx, u_int lines, u_int bg)
 	struct tty_ctx	 ttyctx;
 	u_int		 i;
 
-	screen_write_initctx(ctx, &ttyctx, 1);
+	screen_write_initctx(ctx, &ttyctx, 1, 1);
 	ttyctx.bg = bg;
-	ttyctx.obscured = screen_write_pane_obscured(ctx->wp);
 
 	if (lines == 0)
 		lines = 1;
@@ -1624,7 +1651,7 @@ screen_write_clearendofscreen(struct screen_write_ctx *ctx, u_int bg)
 		ctx->wp->flags |= PANE_REDRAW;
 #endif
 
-	screen_write_initctx(ctx, &ttyctx, 1);
+	screen_write_initctx(ctx, &ttyctx, 1, 1);
 	ttyctx.bg = bg;
 
 	/* Scroll into history if it is enabled and clearing entire screen. */
@@ -1643,7 +1670,7 @@ screen_write_clearendofscreen(struct screen_write_ctx *ctx, u_int bg)
 	screen_write_collect_clear(ctx, s->cy + 1, sy - (s->cy + 1));
 	screen_write_collect_flush(ctx, 0, __func__);
 
-	if (! screen_write_pane_obscured(ctx->wp)) {
+	if (~ttyctx.flags & TTY_CTX_PANE_OBSCURED) {
 		tty_write(tty_cmd_clearendofscreen, &ttyctx);
 		return;
 	}
@@ -1706,7 +1733,7 @@ screen_write_clearstartofscreen(struct screen_write_ctx *ctx, u_int bg)
 		ctx->wp->flags |= PANE_REDRAW;
 #endif
 
-	screen_write_initctx(ctx, &ttyctx, 1);
+	screen_write_initctx(ctx, &ttyctx, 1, 1);
 	ttyctx.bg = bg;
 
 	if (s->cy > 0)
@@ -1719,7 +1746,7 @@ screen_write_clearstartofscreen(struct screen_write_ctx *ctx, u_int bg)
 	screen_write_collect_clear(ctx, 0, s->cy);
 	screen_write_collect_flush(ctx, 0, __func__);
 
-	if (! screen_write_pane_obscured(ctx->wp)) {
+	if (~ttyctx.flags & TTY_CTX_PANE_OBSCURED) {
 		tty_write(tty_cmd_clearstartofscreen, &ttyctx);
 		return;
 	}
@@ -1780,7 +1807,7 @@ screen_write_clearscreen(struct screen_write_ctx *ctx, u_int bg)
 		ctx->wp->flags |= PANE_REDRAW;
 #endif
 
-	screen_write_initctx(ctx, &ttyctx, 1);
+	screen_write_initctx(ctx, &ttyctx, 1, 1);
 	ttyctx.bg = bg;
 
 	/* Scroll into history if it is enabled. */
@@ -1793,7 +1820,7 @@ screen_write_clearscreen(struct screen_write_ctx *ctx, u_int bg)
 
 	screen_write_collect_clear(ctx, 0, sy);
 
-	if (! screen_write_pane_obscured(ctx->wp)) {
+	if (~ttyctx.flags & TTY_CTX_PANE_OBSCURED) {
 		tty_write(tty_cmd_clearscreen, &ttyctx);
 		return;
 	}
@@ -1841,7 +1868,7 @@ screen_write_fullredraw(struct screen_write_ctx *ctx)
 
 	screen_write_collect_flush(ctx, 0, __func__);
 
-	screen_write_initctx(ctx, &ttyctx, 1);
+	screen_write_initctx(ctx, &ttyctx, 1, 0);
 	if (ttyctx.redraw_cb != NULL)
 		ttyctx.redraw_cb(&ttyctx);
 }
@@ -1978,42 +2005,6 @@ screen_write_collect_scroll(struct screen_write_ctx *ctx, u_int bg)
 	TAILQ_INSERT_TAIL(&ctx->s->write_list[s->rlower].items, ci, entry);
 }
 
-/* Return 1 if there is a floating window pane overlapping this pane. */
-static int
-screen_write_pane_obscured(struct window_pane *base_wp)
-{
-	struct window_pane	*wp;
-	struct window		*w;
-	int			 found_self = 0;
-
-	if (base_wp == NULL)
-		return(0);
-	w = base_wp->window;
-
-	TAILQ_FOREACH_REVERSE(wp, &w->z_index, window_panes_zindex, zentry) {
-		if (wp == base_wp) {
-			found_self = 1;
-			continue;
-		}
-		if (found_self && wp->flags & PANE_FLOATING &&
-		    ((wp->yoff >= base_wp->yoff &&
-		    wp->yoff <= base_wp->yoff + (int)base_wp->sy) ||
-		    (wp->yoff + (int)wp->sy >= base_wp->yoff &&
-		    wp->yoff + wp->sy <= base_wp->yoff + base_wp->sy)) &&
-		    ((wp->xoff >= base_wp->xoff &&
-		    wp->xoff <= base_wp->xoff + (int)base_wp->sx) ||
-		    (wp->xoff + (int)wp->sx >= base_wp->xoff &&
-		    wp->xoff + wp->sx <= base_wp->xoff + base_wp->sx))) {
-			log_debug("%s: base %%%u obscured by %%%u "
-			    "(xoff=%u sx=%u vs base xoff=%u sx=%u)", __func__,
-			    base_wp->id, wp->id,
-			    wp->xoff, wp->sx, base_wp->xoff, base_wp->sx);
-			return (1);
-		}
-		}
-	return (0);
-}
-
 /* Flush collected lines. */
 static void
 screen_write_collect_flush(struct screen_write_ctx *ctx, int scroll_only,
@@ -2049,14 +2040,11 @@ screen_write_collect_flush(struct screen_write_ctx *ctx, int scroll_only,
 		if (ctx->scrolled > s->rlower - s->rupper + 1)
 			ctx->scrolled = s->rlower - s->rupper + 1;
 
-		screen_write_initctx(ctx, &ttyctx, 1);
+		screen_write_initctx(ctx, &ttyctx, 1, 1);
 		if (wp != NULL && wp->yoff + wp->sy > wp->window->sy)
 			 ttyctx.orlower -= (wp->yoff + wp->sy - wp->window->sy);
 		ttyctx.num = ctx->scrolled;
 		ttyctx.bg = ctx->bg;
-		ttyctx.obscured = screen_write_pane_obscured(wp);
-		log_debug("%s: obscured=%d for pane %%%u", __func__,
-		    ttyctx.obscured, wp != NULL ? wp->id : 0);
 		tty_write(tty_cmd_scrollup, &ttyctx);
 		if (wp != NULL)
 			log_debug("%s: after scrollup, PANE_REDRAW=%d for %%%u",
@@ -2143,15 +2131,16 @@ screen_write_collect_flush(struct screen_write_ctx *ctx, int scroll_only,
 					continue;
 				screen_write_set_cursor(ctx, wr_start, y);
 				if (ci->type == CLEAR) {
-					screen_write_initctx(ctx, &ttyctx, 1);
+					screen_write_initctx(ctx, &ttyctx, 1, 0);
 					ttyctx.bg = ci->bg;
 					ttyctx.num = wr_length;
 					tty_write(tty_cmd_clearcharacter,
 						  &ttyctx);
 				} else {
-					screen_write_initctx(ctx, &ttyctx, 0);
+					screen_write_initctx(ctx, &ttyctx, 0, 0);
 					ttyctx.cell = &ci->gc;
-					ttyctx.wrapped = ci->wrapped;
+					if (ci->wrapped)
+						ttyctx.flags |= TTY_CTX_WRAPPED;
 					ttyctx.ptr = cl->data + wr_start;
 					ttyctx.num = wr_length;
 					tty_write(tty_cmd_cells, &ttyctx);
@@ -2378,7 +2367,7 @@ screen_write_cell(struct screen_write_ctx *ctx, const struct grid_cell *gc)
 	/* Sanity check cursor position. */
 	if (s->cx > sx - width || s->cy > sy - 1)
 		return;
-	screen_write_initctx(ctx, &ttyctx, 0);
+	screen_write_initctx(ctx, &ttyctx, 0, 0);
 
 	/* Handle overwriting of UTF-8 characters. */
 	gl = grid_get_line(s->grid, s->grid->hsize + s->cy);
@@ -2469,7 +2458,8 @@ screen_write_cell(struct screen_write_ctx *ctx, const struct grid_cell *gc)
 		} else
 			memcpy(&tmp_gc, gc, sizeof tmp_gc);
 		ttyctx.cell = &tmp_gc;
-		ttyctx.num = redraw ? 2 : 0;
+		if (redraw)
+			ttyctx.flags |= TTY_CTX_CELL_DRAW_LINE;
 		for (i=0, vis=0; i < r->used; i++) vis += r->ranges[i].nx;
 		if (vis < width) {
 			/* Wide character or tab partly obscured. Write
@@ -2558,7 +2548,7 @@ 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;
@@ -2617,9 +2607,10 @@ screen_write_combine(struct screen_write_ctx *ctx, const struct grid_cell *gc)
 	 * and what it is going to do now.
 	 */
 	screen_write_set_cursor(ctx, cx - n, cy);
-	screen_write_initctx(ctx, &ttyctx, 0);
+	screen_write_initctx(ctx, &ttyctx, 0, 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);
 
@@ -2705,7 +2696,7 @@ screen_write_setselection(struct screen_write_ctx *ctx, const char *clip,
 {
 	struct tty_ctx	ttyctx;
 
-	screen_write_initctx(ctx, &ttyctx, 0);
+	screen_write_initctx(ctx, &ttyctx, 0, 0);
 	ttyctx.ptr = str;
 	ttyctx.ptr2 = (void *)clip;
 	ttyctx.num = len;
@@ -2720,10 +2711,11 @@ screen_write_rawstring(struct screen_write_ctx *ctx, u_char *str, u_int len,
 {
 	struct tty_ctx	ttyctx;
 
-	screen_write_initctx(ctx, &ttyctx, 0);
+	screen_write_initctx(ctx, &ttyctx, 0, 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);
 }
@@ -2807,7 +2799,7 @@ screen_write_alternateon(struct screen_write_ctx *ctx, struct grid_cell *gc,
 		server_redraw_window_borders(wp->window);
 	}
 
-	screen_write_initctx(ctx, &ttyctx, 1);
+	screen_write_initctx(ctx, &ttyctx, 1, 0);
 	if (ttyctx.redraw_cb != NULL)
 		ttyctx.redraw_cb(&ttyctx);
 }
@@ -2831,7 +2823,7 @@ screen_write_alternateoff(struct screen_write_ctx *ctx, struct grid_cell *gc,
 		server_redraw_window_borders(wp->window);
 	}
 
-	screen_write_initctx(ctx, &ttyctx, 1);
+	screen_write_initctx(ctx, &ttyctx, 1, 0);
 	if (ttyctx.redraw_cb != NULL)
 		ttyctx.redraw_cb(&ttyctx);
 }
diff --git a/tmux.h b/tmux.h
index 57392984..5c6e4ed3 100644
--- a/tmux.h
+++ b/tmux.h
@@ -1055,6 +1055,8 @@ struct screen_write_ctx {
 
 	int				 flags;
 #define SCREEN_WRITE_SYNC 0x1
+#define SCREEN_WRITE_OBSCURED 0x2
+#define SCREEN_WRITE_CHECKED_IF_OBSCURED 0x4
 
 	screen_write_init_ctx_cb	 init_ctx_cb;
 	void				*arg;
@@ -1733,18 +1735,19 @@ 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
+#define TTY_CTX_PANE_OBSCURED 0x80
 
-	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
@@ -1773,14 +1776,10 @@ 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;
 	u_int			 wsy;
-
-	/* tty partly obscured, it will need to be surgically scrolled. */
-	u_int			 obscured;
 };
 
 /* Saved message entry. */
diff --git a/tty.c b/tty.c
index 6e622804..121e3b85 100644
--- a/tty.c
+++ b/tty.c
@@ -1099,7 +1099,7 @@ tty_redraw_region(struct tty *tty, const struct tty_ctx *ctx)
 	log_debug("%s: %s orlower=%u orupper=%u sy=%u large=%d", __func__,
 	    c->name, ctx->orlower, ctx->orupper, ctx->sy,
 	    tty_large_region(tty, ctx));
-	if (tty_large_region(tty, ctx) && !ctx->obscured) {
+	if (tty_large_region(tty, ctx) && ~ctx->flags & TTY_CTX_PANE_OBSCURED) {
 		log_debug("%s: %s large region redraw", __func__, c->name);
 		ctx->redraw_cb(ctx);
 		return;
@@ -1118,7 +1118,7 @@ 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 ||
@@ -1429,11 +1429,11 @@ tty_draw_pane(struct tty *tty, const struct tty_ctx *ctx, u_int py)
 	struct visible_range	*ri;
 	u_int			 nx = ctx->sx, i, px, x, rx, ry;
 
-	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) {
 		if (wp) {
-			if (ctx->obscured) {
+			if (ctx->flags & TTY_CTX_PANE_OBSCURED) {
 				/*
 				 * Floating pane is present: use physical
 				 * coordinates and clip to visible ranges to
@@ -1644,7 +1644,7 @@ 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)
@@ -1693,13 +1693,12 @@ 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_CTX_PANE_OBSCURED)) ||
 	    !tty_full_width(tty, ctx) ||
 	    tty_fake_bce(tty, &ctx->defaults, ctx->bg) ||
 	    (!tty_term_has(tty->term, TTYC_ICH) &&
 	    !tty_term_has(tty->term, TTYC_ICH1)) ||
-	    c->overlay_check != NULL ||
-	    ctx->obscured) {
+	    c->overlay_check != NULL) {
 		tty_draw_pane(tty, ctx, ctx->ocy);
 		return;
 	}
@@ -1717,13 +1716,12 @@ 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_CTX_PANE_OBSCURED) ||
 	    !tty_full_width(tty, ctx) ||
 	    tty_fake_bce(tty, &ctx->defaults, ctx->bg) ||
 	    (!tty_term_has(tty->term, TTYC_DCH) &&
 	    !tty_term_has(tty->term, TTYC_DCH1)) ||
-	    c->overlay_check != NULL ||
-	    ctx->obscured) {
+	    c->overlay_check != NULL) {
 		tty_draw_pane(tty, ctx, ctx->ocy);
 		return;
 	}
@@ -1750,15 +1748,14 @@ 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_CTX_PANE_OBSCURED)) ||
 	    !tty_full_width(tty, ctx) ||
 	    tty_fake_bce(tty, &ctx->defaults, ctx->bg) ||
 	    !tty_term_has(tty->term, TTYC_CSR) ||
 	    !tty_term_has(tty->term, TTYC_IL1) ||
 	    ctx->sx == 1 ||
 	    ctx->sy == 1 ||
-	    c->overlay_check != NULL ||
-	    ctx->obscured) {
+	    c->overlay_check != NULL) {
 		tty_redraw_region(tty, ctx);
 		return;
 	}
@@ -1779,15 +1776,14 @@ 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_CTX_PANE_OBSCURED) ||
 	    !tty_full_width(tty, ctx) ||
 	    tty_fake_bce(tty, &ctx->defaults, ctx->bg) ||
 	    !tty_term_has(tty->term, TTYC_CSR) ||
 	    !tty_term_has(tty->term, TTYC_DL1) ||
 	    ctx->sx == 1 ||
 	    ctx->sy == 1 ||
-	    c->overlay_check != NULL ||
-	    ctx->obscured) {
+	    c->overlay_check != NULL) {
 		tty_redraw_region(tty, ctx);
 		return;
 	}
@@ -1840,7 +1836,7 @@ 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) ||
@@ -1874,7 +1870,7 @@ 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) ||
@@ -1915,14 +1911,13 @@ 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_CTX_PANE_OBSCURED) ||
 	    (!tty_full_width(tty, ctx) && !tty_use_margin(tty)) ||
 	    tty_fake_bce(tty, &ctx->defaults, 8) ||
 	    !tty_term_has(tty->term, TTYC_CSR) ||
 	    ctx->sx == 1 ||
 	    ctx->sy == 1 ||
-	    c->overlay_check != NULL ||
-	    ctx->obscured) {
+	    c->overlay_check != NULL) {
 		tty_redraw_region(tty, ctx);
 		return;
 	}
@@ -1955,7 +1950,7 @@ 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_CTX_PANE_OBSCURED) ||
 	    (!tty_full_width(tty, ctx) && !tty_use_margin(tty)) ||
 	    tty_fake_bce(tty, &ctx->defaults, 8) ||
 	    !tty_term_has(tty->term, TTYC_CSR) ||
@@ -1963,8 +1958,7 @@ tty_cmd_scrolldown(struct tty *tty, const struct tty_ctx *ctx)
 	    !tty_term_has(tty->term, TTYC_RIN)) ||
 	    ctx->sx == 1 ||
 	    ctx->sy == 1 ||
-	    c->overlay_check != NULL ||
-	    ctx->obscured) {
+	    c->overlay_check != NULL) {
 		tty_redraw_region(tty, ctx);
 		return;
 	}
@@ -2058,7 +2052,7 @@ 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|TTY_CTX_PANE_OBSCURED)) {
 		ctx->redraw_cb(ctx);
 		return;
 	}
@@ -2090,7 +2084,7 @@ 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;
@@ -2120,7 +2114,7 @@ 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);
 }
 
@@ -2135,10 +2129,10 @@ 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 ||
@@ -2401,20 +2395,23 @@ 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
@@ -2593,7 +2590,7 @@ 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 ||