diff --git a/scheme/layout.scm b/scheme/layout.scm
index 412d2d1..f791813 100644
--- a/scheme/layout.scm
+++ b/scheme/layout.scm
@@ -51,12 +51,6 @@
 		    (append result (list (+ count 3))))
 	      (loop (+ count 1) result))))))
 
-;;expression as string
-(define (exp->string exp)
-  (let ((exp-port (open-output-string)))
-    (write exp exp-port)
-    (get-output-string exp-port)))
-
 (define (sublist l pos k)
   (let ((tmp (list-tail l pos)))
     (reverse (list-tail (reverse tmp) 
diff --git a/scheme/nuit-packages.scm b/scheme/nuit-packages.scm
index 8637986..d9ed6c0 100644
--- a/scheme/nuit-packages.scm
+++ b/scheme/nuit-packages.scm
@@ -8,6 +8,15 @@
   (open scheme conditions handle)
   (files handle-fatal-error))
 
+(define-interface utils-interface
+  (export display-to-string
+          exp->string))
+
+(define-structure utils utils-interface
+  (open scheme
+        srfi-6)
+  (files utils))
+
 ;;; history data structure
 
 (define-interface history-interface
@@ -35,7 +44,6 @@
 	  get-marked-positions-1
 	  get-marked-positions-2
 	  get-marked-positions-3
-	  exp->string
 	  sublist
 
 	  fill-up-string
@@ -70,7 +78,6 @@
 
 (define-structure layout layout-interface
   (open scheme-with-scsh
-	srfi-6			;; basic string ports
 	define-record-types
 	let-opt
 	locks
@@ -144,6 +151,7 @@
 	pps
 	plugin
 	layout
+        utils
 	select-list
 	tty-debug)
   (files process))
@@ -159,6 +167,7 @@
         dirlist-view-plugin
         fs-object
         plugin
+        utils
         layout
         select-list
         (subset focus-table (make-focus-object-reference))
@@ -198,6 +207,7 @@
 	focus-table
 	objects
 	layout
+        utils
 	fs-object
 	select-list
 	plugin
@@ -262,6 +272,7 @@
 
         tty-debug
 	objects
+        utils
 	layout)
   (files std-viewer))
 
@@ -320,7 +331,7 @@
 	(subset focus-table (make-focus-object-reference))
 	tty-debug
 	plugin
-	layout
+        utils
 	ncurses)
   (files select-list))
 
@@ -367,6 +378,7 @@
         focus-table
 	ncurses
         layout
+        utils
         select-list
         tty-debug
         plugin)
diff --git a/scheme/user-group-info.scm b/scheme/user-group-info.scm
index 9c251e7..d025bc8 100644
--- a/scheme/user-group-info.scm
+++ b/scheme/user-group-info.scm
@@ -246,7 +246,7 @@
 
     (define (prepare-selection-for-command-mode infos)
       (string-join
-       (map value->string
+       (map display-to-string
             (map group-info-element->value infos))))
     
     (define (prepare-selection-for-scheme-mode infos)
@@ -307,13 +307,6 @@
         (else
          (error "unknown message in make-group-info-browser" message))))))
 
-(define (value->string val)
-  (cond ((string? val) val)
-        ((number? val) (number->string val))
-        ((boolean? val) (if val "#t" "#f"))
-        (else
-         (error "unknwon value in value->string" val))))
-
 (define (make-user-info-browser ui buffer)
   (let ((ui ui)
         (buffer buffer)
@@ -335,7 +328,7 @@
  
     (define (prepare-selection-for-command-mode infos)
       (string-join
-       (map value->string
+       (map display-to-string
             (map user-info-element->value infos))))
     
     (define (prepare-selection-for-scheme-mode infos)