--- a/UIPainterView.st	Mon Feb 13 09:54:17 2006 +0100
+++ b/UIPainterView.st	Mon Feb 13 09:54:24 2006 +0100
@@ -134,19 +134,27 @@
     self className:aName
 !
 
+class:aClass superclassName:aSuperclassName selector:aSelector
+    self assert:(aClass isBehavior).
+    className      := aClass name.
+    superclassName := aSuperclassName.
+    methodName     := aSelector.
+!
+
 className
     ^ className
 !
 
 className:aName
+    self assert:(aName isString).
     className := aName
 !
 
 className:aClassName superclassName:aSuperclassName selector:aSelector
+    self assert:(aClassName isString).
     className      := aClassName.
     superclassName := aSuperclassName.
     methodName     := aSelector.
-
 !
 
 methodName