--- st.c
+++ st.c
@@ -1435,89 +1598,93 @@ tsetchar(Rune u, const Glyph *attr, int x, int y)
 	} else if (term.line[y][x].mode & ATTR_WDUMMY) {
 		term.line[y][x-1].u = ' ';
 		term.line[y][x-1].mode &= ~ATTR_WIDE;
-	}
+  }
 
 	term.dirty[y] = 1;
 	term.line[y][x] = *attr;
 	term.line[y][x].u = u;
+	term.line[y][x].mode |= ATTR_SET;
 }
 
 void
-tclearregion(int x1, int y1, int x2, int y2)
+tclearglyph(Glyph *gp, int usecurattr)
 {
-	int x, y, temp;
-	Glyph *gp;
+	if (usecurattr) {
+		gp->fg = term.c.attr.fg;
+		gp->bg = term.c.attr.bg;
+	} else {
+		gp->fg = defaultfg;
+		gp->bg = defaultbg;
+	}
+	gp->mode = ATTR_NULL;
+	gp->u = ' ';
+}
 
-	if (x1 > x2)
-		temp = x1, x1 = x2, x2 = temp;
-	if (y1 > y2)
-		temp = y1, y1 = y2, y2 = temp;
+void
+tclearregion(int x1, int y1, int x2, int y2, int usecurattr)
+{
+	int x, y;
 
-	LIMIT(x1, 0, term.col-1);
-	LIMIT(x2, 0, term.col-1);
-	LIMIT(y1, 0, term.row-1);
-	LIMIT(y2, 0, term.row-1);
+	/* regionselected() takes relative coordinates */
+	if (regionselected(x1+term.scr, y1+term.scr, x2+term.scr, y2+term.scr))
+		selremove();
 
 	for (y = y1; y <= y2; y++) {
 		term.dirty[y] = 1;
-		for (x = x1; x <= x2; x++) {
-			gp = &term.line[y][x];
-			if (selected(x, y))
-				selclear();
-			gp->fg = term.c.attr.fg;
-			gp->bg = term.c.attr.bg;
-			gp->mode = 0;
-			gp->u = ' ';
-		}
+		for (x = x1; x <= x2; x++)
+			tclearglyph(&term.line[y][x], usecurattr);
 	}
 }
 
 void
 tdeletechar(int n)
 {
-	int dst, src, size;
-	Glyph *line;
-
-	LIMIT(n, 0, term.col - term.c.x);
+	int src, dst, size;
+	Line line;
 
+	if (n <= 0)
+		return;
 	dst = term.c.x;
-	src = term.c.x + n;
+	src = MIN(term.c.x + n, term.col);
 	size = term.col - src;
-	line = term.line[term.c.y];
-
-	memmove(&line[dst], &line[src], size * sizeof(Glyph));
-	tclearregion(term.col-n, term.c.y, term.col-1, term.c.y);
+	if (size > 0) { /* otherwise src would point beyond the array
+	                   https://stackoverflow.com/questions/29844298 */
+		line = term.line[term.c.y];
+		memmove(&line[dst], &line[src], size * sizeof(Glyph));
+	}
+	tclearregion(dst + size, term.c.y, term.col - 1, term.c.y, 1);
 }
 
 void
 tinsertblank(int n)
 {
-	int dst, src, size;
-	Glyph *line;
+	int src, dst, size;
+	Line line;
 
-	LIMIT(n, 0, term.col - term.c.x);
-
-	dst = term.c.x + n;
+	if (n <= 0)
+		return;
+	dst = MIN(term.c.x + n, term.col);
 	src = term.c.x;
 	size = term.col - dst;
-	line = term.line[term.c.y];
-
-	memmove(&line[dst], &line[src], size * sizeof(Glyph));
-	tclearregion(src, term.c.y, dst - 1, term.c.y);
+	if (size > 0) { /* otherwise dst would point beyond the array */
+		line = term.line[term.c.y];
+		memmove(&line[dst], &line[src], size * sizeof(Glyph));
+	}
+	tclearregion(src, term.c.y, dst - 1, term.c.y, 1);
 }
 
 void
 tinsertblankline(int n)
 {
 	if (BETWEEN(term.c.y, term.top, term.bot))
-		tscrolldown(term.c.y, n, 0);
+		tscrolldown(term.c.y, n);
 }
 
 void
 tdeleteline(int n)
 {
 	if (BETWEEN(term.c.y, term.top, term.bot))
-		tscrollup(term.c.y, n, 0);
+		tscrollup(term.c.y, term.bot, n, SCROLL_NOSAVEHIST);
 }
 
 int32_t
@@ -2001,9 +2173,9 @@ csihandle(void)
 		break;
 	case 'n': /* DSR – Device Status Report (cursor position) */
 		if (csiescseq.arg[0] == 6) {
-			len = snprintf(buf, sizeof(buf), "\033[%i;%iR",
+			n = snprintf(buf, sizeof(buf), "\033[%i;%iR",
 					term.c.y+1, term.c.x+1);
-			ttywrite(buf, len, 0);
+			ttywrite(buf, n, 0);
 		}
 		break;
 	case 'r': /* DECSTBM -- Set Scrolling Region */