Fix drawing fields containing empty lines

examples/messeji/game/game.go

@@ -72,13 +72,13 @@ func NewDemoGame() *game {
 		},
 	}
 
-	g.buffer.SetText(strings.TrimSpace(initialText) + "\n")
+	g.buffer.SetText(strings.TrimSpace(initialText))
 
 	g.input.SetHandleKeyboard(true)
 	g.input.SetSelectedFunc(func() (accept bool) {
 		log.Printf("Input: %s", g.input.Text())
 
-		g.buffer.Write([]byte(fmt.Sprintf("Input: %s\n", g.input.Text())))
+		g.buffer.Write([]byte(fmt.Sprintf("\nInput: %s", g.input.Text())))
 
 		return true
 	})

textfield.go

@@ -534,6 +534,13 @@ func (f *TextField) wrapContent(withScrollBar bool) {
 	}
 	f.bufferWrapped = f.bufferWrapped[:0]
 	for _, line := range strings.Split(buffer, "\n") {
+		// BoundString returns 0 for strings containing only whitespace.
+		if strings.TrimSpace(line) == "" {
+			f.bufferWrapped = append(f.bufferWrapped, "")
+			f.lineWidths = append(f.lineWidths, 0)
+			continue
+		}
+
 		l := len(line)
 		var start int
 		var end int