Index: main/display-string.lisp
===================================================================
--- main/display-string.lisp	(revision main,28)
+++ main/display-string.lisp	(revision main,49)
@@ -1,5 +1,5 @@
 (defpackage #:tui-display-string
   (:use #:cl #:cl-ppcre #:dso-lex #:tui-cursor #:tui-output #:tui-window)
-  (:export #:enquote #:dequote #:render))
+  (:export #:enquote #:dequote #:render #:renderlen))
 
 (in-package #:tui-display-string)
@@ -38,6 +38,7 @@
       (escape 0))))
 
-(defun renderlen (parts)
-  (let ((lens (mapcar 'renderlen-part parts)))
+(defun renderlen (dstr)
+  (let* ((parts (scan-dstring dstr))
+         (lens (mapcar 'renderlen-part parts)))
     (reduce '+ lens)))