diff --git a/screen-redraw.c b/screen-redraw.c
index dd5886b2..fc2817ce 100644
--- a/screen-redraw.c
+++ b/screen-redraw.c
@@ -49,9 +49,15 @@ const struct grid_cell screen_redraw_border_cell = {
 	{ { ' ' }, 0, 1, 1 }, GRID_ATTR_CHARSET, 0, 8, 8, 0
 };
 
+enum screen_redraw_border_type {
+	SCREEN_REDRAW_OUTSIDE,
+	SCREEN_REDRAW_INSIDE,
+	SCREEN_REDRAW_BORDER
+};
+
 /* Return if window has only two panes. */
 static int
-screen_redraw_two_panes(struct window *w)
+screen_redraw_two_panes(struct window *w, int direction)
 {
 	struct window_pane	*wp;
 
@@ -60,99 +66,176 @@ screen_redraw_two_panes(struct window *w)
 		return (0); /* one pane */
 	if (TAILQ_NEXT(wp, entry) != NULL)
 		return (0); /* more than two panes */
+	if (direction == 0 && wp->xoff == 0)
+		return (0);
+	if (direction == 1 && wp->yoff == 0)
+		return (0);
 	return (1);
 }
 
-/* Check if cell is on the border of a particular pane. */
-static int
-screen_redraw_cell_border1(struct window_pane *wp, u_int px, u_int py,
+/* Check if cell is on the border of a pane. */
+static enum screen_redraw_border_type
+screen_redraw_pane_border(struct window_pane *wp, u_int px, u_int py,
     int pane_status)
 {
 	u_int	ex = wp->xoff + wp->sx, ey = wp->yoff + wp->sy;
 
 	/* Inside pane. */
 	if (px >= wp->xoff && px < ex && py >= wp->yoff && py < ey)
-		return (0);
+		return (SCREEN_REDRAW_INSIDE);
 
 	/* Left/right borders. */
 	if (pane_status == PANE_STATUS_OFF) {
-		if (screen_redraw_two_panes(wp->window)) {
+		if (screen_redraw_two_panes(wp->window, 0)) {
 			if (wp->xoff == 0 && px == wp->sx && py <= wp->sy / 2)
-				return (2);
+				return (SCREEN_REDRAW_BORDER);
 			if (wp->xoff != 0 &&
 			    px == wp->xoff - 1 &&
 			    py > wp->sy / 2)
-				return (1);
+				return (SCREEN_REDRAW_BORDER);
 		} else {
 			if ((wp->yoff == 0 || py >= wp->yoff - 1) && py <= ey) {
 				if (wp->xoff != 0 && px == wp->xoff - 1)
-					return (1);
+					return (SCREEN_REDRAW_BORDER);
 				if (px == ex)
-					return (2);
+					return (SCREEN_REDRAW_BORDER);
 			}
 		}
 	} else {
 		if ((wp->yoff == 0 || py >= wp->yoff - 1) && py <= ey) {
 			if (wp->xoff != 0 && px == wp->xoff - 1)
-				return (1);
+				return (SCREEN_REDRAW_BORDER);
 			if (px == ex)
-				return (2);
+				return (SCREEN_REDRAW_BORDER);
 		}
 	}
 
 	/* Top/bottom borders. */
 	if (pane_status == PANE_STATUS_OFF) {
-		if (screen_redraw_two_panes(wp->window)) {
+		if (screen_redraw_two_panes(wp->window, 1)) {
 			if (wp->yoff == 0 && py == wp->sy && px <= wp->sx / 2)
-				return (4);
+				return (SCREEN_REDRAW_BORDER);
 			if (wp->yoff != 0 &&
 			    py == wp->yoff - 1 &&
 			    px > wp->sx / 2)
-				return (3);
+				return (SCREEN_REDRAW_BORDER);
 		} else {
 			if ((wp->xoff == 0 || px >= wp->xoff - 1) && px <= ex) {
 				if (wp->yoff != 0 && py == wp->yoff - 1)
-					return (3);
+					return (SCREEN_REDRAW_BORDER);
 				if (py == ey)
-					return (4);
+					return (SCREEN_REDRAW_BORDER);
 			}
 		}
 	} 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 (3);
+				return (SCREEN_REDRAW_BORDER);
 		}
 	} else {
 		if ((wp->xoff == 0 || px >= wp->xoff - 1) && px <= ex) {
 			if (py == ey)
-				return (4);
+				return (SCREEN_REDRAW_BORDER);
 		}
 	}
 
 	/* Outside pane. */
-	return (-1);
+	return (SCREEN_REDRAW_OUTSIDE);
 }
 
-/* Check if a cell is on the pane border. */
+/* Check if a cell is on a border. */
 static int
 screen_redraw_cell_border(struct client *c, u_int px, u_int py, int pane_status)
 {
 	struct window		*w = c->session->curw->window;
 	struct window_pane	*wp;
-	int			 retval;
+
+	/* On the window border? */
+	if (px == w->sx || py == w->sy)
+		return (1);
+
+	/* Outside the window? */
+	if (px > w->sx || py > w->sy)
+		return (0);
 
 	/* Check all the panes. */
 	TAILQ_FOREACH(wp, &w->panes, entry) {
 		if (!window_pane_visible(wp))
 			continue;
-		retval = screen_redraw_cell_border1(wp, px, py, pane_status);
-		if (retval != -1)
-			return (!!retval);
+		switch (screen_redraw_pane_border(wp, px, py, pane_status)) {
+		case SCREEN_REDRAW_INSIDE:
+			return (0);
+		case SCREEN_REDRAW_BORDER:
+			return (1);
+		case SCREEN_REDRAW_OUTSIDE:
+			break;
+		}
 	}
 
 	return (0);
 }
 
+/* Work out type of border cell from surrounding cells. */
+static int
+screen_redraw_type_of_cell(struct client *c, u_int px, u_int py,
+    int pane_status)
+{
+	struct window	*w = c->session->curw->window;
+	u_int		 sx = w->sx, sy = w->sy;
+	int		 borders = 0;
+
+	/*
+	 * Construct a bitmask of whether the cells to the left (bit 4), right,
+	 * top, and bottom (bit 1) of this cell are borders.
+	 */
+	if (px == 0 || screen_redraw_cell_border(c, px - 1, py, pane_status))
+		borders |= 8;
+	if (px <= sx && screen_redraw_cell_border(c, px + 1, py, pane_status))
+		borders |= 4;
+	if (pane_status == PANE_STATUS_TOP) {
+		if (py != 0 &&
+		    screen_redraw_cell_border(c, px, py - 1, pane_status))
+			borders |= 2;
+	} else {
+		if (py == 0 ||
+		    screen_redraw_cell_border(c, px, py - 1, pane_status))
+		    borders |= 2;
+	}
+	if (py <= sy && screen_redraw_cell_border(c, px, py + 1, pane_status))
+		borders |= 1;
+
+	/*
+	 * Figure out what kind of border this cell is. Only one bit set
+	 * doesn't make sense (can't have a border cell with no others
+	 * connected).
+	 */
+	switch (borders) {
+	case 15:	/* 1111, left right top bottom */
+		return (CELL_JOIN);
+	case 14:	/* 1110, left right top */
+		return (CELL_BOTTOMJOIN);
+	case 13:	/* 1101, left right bottom */
+		return (CELL_TOPJOIN);
+	case 12:	/* 1100, left right */
+		return (CELL_TOPBOTTOM);
+	case 11:	/* 1011, left top bottom */
+		return (CELL_RIGHTJOIN);
+	case 10:	/* 1010, left top */
+		return (CELL_BOTTOMRIGHT);
+	case 9:		/* 1001, left bottom */
+		return (CELL_TOPRIGHT);
+	case 7:		/* 0111, right top bottom */
+		return (CELL_LEFTJOIN);
+	case 6:		/* 0110, right top */
+		return (CELL_BOTTOMLEFT);
+	case 5:		/* 0101, right bottom */
+		return (CELL_TOPLEFT);
+	case 3:		/* 0011, top bottom */
+		return (CELL_LEFTRIGHT);
+	}
+	return (CELL_OUTSIDE);
+}
+
 /* Check if cell inside a pane. */
 static int
 screen_redraw_check_cell(struct client *c, u_int px, u_int py, int pane_status,
@@ -160,13 +243,15 @@ screen_redraw_check_cell(struct client *c, u_int px, u_int py, int pane_status,
 {
 	struct window		*w = c->session->curw->window;
 	struct window_pane	*wp;
-	int			 borders, border;
+	int			 border;
 	u_int			 right, line;
 
 	*wpp = NULL;
 
 	if (px > w->sx || py > w->sy)
 		return (CELL_OUTSIDE);
+	if (px == w->sx || py == w->sy) /* window border */
+		return (screen_redraw_type_of_cell(c, px, py, pane_status));
 
 	if (pane_status != PANE_STATUS_OFF) {
 		wp = w->active;
@@ -196,72 +281,16 @@ screen_redraw_check_cell(struct client *c, u_int px, u_int py, int pane_status,
 			goto next2;
 		*wpp = wp;
 
-		/* If outside the pane and its border, skip it. */
-		if ((wp->xoff != 0 && px < wp->xoff - 1) ||
-		    px > wp->xoff + wp->sx ||
-		    (wp->yoff != 0 && py < wp->yoff - 1) ||
-		    py > wp->yoff + wp->sy)
-			goto next2;
-
-		/* If definitely inside, return. If not on border, skip. */
-		border = screen_redraw_cell_border1(wp, px, py, pane_status);
-		if (border == 0)
+		/*
+		 * If definitely inside, return. If not on border, skip.
+		 * Otherwise work out the cell.
+		 */
+		border = screen_redraw_pane_border(wp, px, py, pane_status);
+		if (border == SCREEN_REDRAW_INSIDE)
 			return (CELL_INSIDE);
-		if (border == -1)
+		if (border == SCREEN_REDRAW_OUTSIDE)
 			goto next2;
-
-		/*
-		 * Construct a bitmask of whether the cells to the left (bit
-		 * 4), right, top, and bottom (bit 1) of this cell are borders.
-		 */
-		borders = 0;
-		if (px == 0 ||
-		    screen_redraw_cell_border(c, px - 1, py, pane_status))
-			borders |= 8;
-		if (px <= w->sx &&
-		    screen_redraw_cell_border(c, px + 1, py, pane_status))
-			borders |= 4;
-		if (pane_status == PANE_STATUS_TOP &&
-		    py != 0 &&
-		    screen_redraw_cell_border(c, px, py - 1, pane_status))
-			borders |= 2;
-		else if (pane_status != PANE_STATUS_TOP &&
-		    (py == 0 ||
-		    screen_redraw_cell_border(c, px, py - 1, pane_status)))
-			borders |= 2;
-		if (py <= w->sy &&
-		    screen_redraw_cell_border(c, px, py + 1, pane_status))
-			borders |= 1;
-
-		/*
-		 * Figure out what kind of border this cell is. Only one bit
-		 * set doesn't make sense (can't have a border cell with no
-		 * others connected).
-		 */
-		switch (borders) {
-		case 15:	/* 1111, left right top bottom */
-			return (CELL_JOIN);
-		case 14:	/* 1110, left right top */
-			return (CELL_BOTTOMJOIN);
-		case 13:	/* 1101, left right bottom */
-			return (CELL_TOPJOIN);
-		case 12:	/* 1100, left right */
-			return (CELL_TOPBOTTOM);
-		case 11:	/* 1011, left top bottom */
-			return (CELL_RIGHTJOIN);
-		case 10:	/* 1010, left top */
-			return (CELL_BOTTOMRIGHT);
-		case 9:		/* 1001, left bottom */
-			return (CELL_TOPRIGHT);
-		case 7:		/* 0111, right top bottom */
-			return (CELL_LEFTJOIN);
-		case 6:		/* 0110, right top */
-			return (CELL_BOTTOMLEFT);
-		case 5:		/* 0101, right bottom */
-			return (CELL_TOPLEFT);
-		case 3:		/* 0011, top bottom */
-			return (CELL_LEFTRIGHT);
-		}
+		return (screen_redraw_type_of_cell(c, px, py, pane_status));
 
 	next2:
 		wp = TAILQ_NEXT(wp, entry);
@@ -277,12 +306,12 @@ static int
 screen_redraw_check_is(u_int px, u_int py, int pane_status,
     struct window_pane *wp)
 {
-	int	border;
+	enum screen_redraw_border_type	border;
 
-	border = screen_redraw_cell_border1(wp, px, py, pane_status);
-	if (border == 0 || border == -1)
-		return (0);
-	return (1);
+	border = screen_redraw_pane_border(wp, px, py, pane_status);
+	if (border == SCREEN_REDRAW_BORDER)
+		return (1);
+	return (0);
 }
 
 /* Update pane status. */