--- a/Tools_OrganizerCanvas.st	Fri Apr 26 11:48:22 2013 +0200
+++ b/Tools_OrganizerCanvas.st	Fri Apr 26 11:48:32 2013 +0200
@@ -4852,7 +4852,7 @@
         ^ self.
     ].
     orgMode == OrganizerCanvas organizerModeHierarchy ifTrue:[
-        classHierarchyTopClassHolder value:nil.
+        classHierarchyTopClassHolder notNil ifTrue:[ classHierarchyTopClassHolder value:nil].
         ^ self.
     ].
     orgMode == OrganizerCanvas organizerModePackageDiagram ifTrue:[
@@ -5044,10 +5044,10 @@
 !OrganizerCanvas class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libtool/Tools_OrganizerCanvas.st,v 1.53 2013-04-02 09:34:11 stefan Exp $'
+    ^ '$Header: /cvs/stx/stx/libtool/Tools_OrganizerCanvas.st,v 1.54 2013-04-26 09:48:32 cg Exp $'
 !
 
 version_CVS
-    ^ '$Header: /cvs/stx/stx/libtool/Tools_OrganizerCanvas.st,v 1.53 2013-04-02 09:34:11 stefan Exp $'
+    ^ '$Header: /cvs/stx/stx/libtool/Tools_OrganizerCanvas.st,v 1.54 2013-04-26 09:48:32 cg Exp $'
 ! !