Check for unknwon messages in std-viewer

scheme/nuit-packages.scm

@@ -149,6 +149,7 @@
 (define-structure standard-viewer
     (export make-standard-viewer)
   (open scheme
+        srfi-23
 
         tty-debug
 	objects

scheme/std-viewer.scm

@@ -6,6 +6,7 @@
                (exp->string value)
                (result-buffer-num-cols buffer))))
     (lambda (message)      
+      (debug-message "message for make-standard-viewer" message)
       (cond
        ((eq? message 'paint)
 	(lambda (self win buffer have-focus?)
@@ -15,5 +16,7 @@
 
        ((eq? message 'key-press)
 	(lambda (self . ignore)
-	  self))))))
+	  self))
+       (else
+        (error "unknwon message in make-standard-viewer" message))))))