Draw the counter reset as a labelled rule across the table

main.go

@@ -461,7 +461,7 @@ func run(aName, bName, sizesArg, patArg string,
 				d.resetErrors()
 			}
 			stats.sinceHeader = 0
-			fmt.Println(paint("error counts reset", cDim))
+			fmt.Println(stats.rule("error counts reset"))
 		case now := <-tick.C:
 			secs := now.Sub(last).Seconds()
 			last = now

render.go

@@ -111,6 +111,31 @@ func (t *streamTable) headerLines() []string {
 	}
 }
 
+func (t *streamTable) width() int {
+	w := 0
+	for i, c := range t.cols {
+		w += c.width
+		if i > 0 {
+			w++
+		}
+	}
+	return w
+}
+
+// A labelled horizontal rule spanning the table, for marking a break in the
+// stream of rows.
+func (t *streamTable) rule(label string) string {
+	const lead = 3
+	text := " " + label + " "
+	trail := t.width() - lead - visWidth(text)
+	if trail < 0 {
+		trail = 0
+	}
+	return paint(strings.Repeat("─", lead), cGrey) +
+		paint(text, cDim) +
+		paint(strings.Repeat("─", trail), cGrey)
+}
+
 func (t *streamTable) emit(cells []string) []string {
 	var out []string
 	if t.sinceHeader == 0 || (t.headerEvery > 0 && t.sinceHeader >= t.headerEvery) {