--- a/extensions.st	Wed Jun 29 20:23:17 2011 +0200
+++ b/extensions.st	Thu Jun 30 17:41:22 2011 +0200
@@ -2,78 +2,102 @@
 
 !UserPreferences methodsFor:'accessing - history manager'!
 
+historyManagerAllowEditOfHistory
+    "useful if you have 'beginner students', to prevent them from changing the history"
+
+    ^self 
+        at: #'history-manager.allow-edit-of-history'
+        ifAbsentPut:false
+
+    "Modified (Format): / 30-06-2011 / 17:07:33 / cg"
+    "Modified (Comment): / 30-06-2011 / 17:09:24 / cg"
+! !
+
+!UserPreferences methodsFor:'accessing - history manager'!
+
 historyManagerModificationLimit
+    "the time-delta within which the history manager does not treat a change as a new one"
 
     ^self 
         at: #'history-manager.modification-limit'
         ifAbsentPut: 3600 "/one hour"
 
     "Created: / 04-10-2008 / 11:55:56 / Jan Vrany <vranyj1@fel.cvut.cz>"
+    "Modified (Comment): / 30-06-2011 / 17:25:09 / cg"
 ! !
 
 !UserPreferences methodsFor:'accessing - history manager'!
 
 historyManagerModificationLimit: sec
+    "the time-delta within which the history manager does not treat a change as a new one"
 
     ^self 
         at: #'history-manager.modification-limit'
         put: sec
 
     "Created: / 04-10-2008 / 11:56:23 / Jan Vrany <vranyj1@fel.cvut.cz>"
+    "Modified (Comment): / 30-06-2011 / 17:25:13 / cg"
 ! !
 
 !UserPreferences methodsFor:'accessing - history manager'!
 
 historyManagerSignature
+    "the signature added by the history manager"
 
     ^self historyManagerSignatures
         at: (Array with: OperatingSystem getHostName with: OperatingSystem getLoginName)
-        ifAbsent:
-            [HistoryManager askForSignature]
+        ifAbsent: [HistoryManager askForSignature]
 
     "Created: / 04-10-2008 / 12:06:58 / Jan Vrany <vranyj1@fel.cvut.cz>"
+    "Modified (Format): / 30-06-2011 / 17:26:24 / cg"
 ! !
 
 !UserPreferences methodsFor:'accessing - history manager'!
 
 historyManagerSignature: aString
+    "the signature added by the history manager"
 
     ^self historyManagerSignatures
         at: (Array with: OperatingSystem getHostName with: OperatingSystem getLoginName)
         put: aString
 
     "Created: / 04-10-2008 / 11:54:53 / Jan Vrany <vranyj1@fel.cvut.cz>"
+    "Modified (Comment): / 30-06-2011 / 17:25:31 / cg"
 ! !
 
 !UserPreferences methodsFor:'accessing - history manager'!
 
 historyManagerSignatures
+    "the signatures added by the history manager"
 
     ^self 
         at: #'history-manager.signatures'
         ifAbsentPut: [Dictionary new]
 
     "
-        UserPreferences current historyManagerSignatures
+     UserPreferences current historyManagerSignatures
     "
 
     "Created: / 04-10-2008 / 11:52:40 / Jan Vrany <vranyj1@fel.cvut.cz>"
     "Modified: / 22-08-2009 / 11:00:12 / Jan Vrany <vranyj1@fel.cvut.cz>"
+    "Modified (Comment): / 30-06-2011 / 17:27:14 / cg"
 ! !
 
 !UserPreferences methodsFor:'accessing - history manager'!
 
 historyManagerSignatures: aDictionary
+    "the signatures added by the history manager"
 
     ^self 
         at: #'history-manager.signatures'
         ifAbsentPut: aDictionary
 
     "Created: / 04-10-2008 / 11:52:58 / Jan Vrany <vranyj1@fel.cvut.cz>"
+    "Modified (Comment): / 30-06-2011 / 17:26:48 / cg"
 ! !
 
 !stx_libbasic3 class methodsFor:'documentation'!
 
 extensionsVersion_CVS
-    ^ '$Header: /cvs/stx/stx/libbasic3/extensions.st,v 1.2 2011-06-28 21:00:59 vrany Exp $'
+    ^ '$Header: /cvs/stx/stx/libbasic3/extensions.st,v 1.3 2011-06-30 15:41:22 cg Exp $'
 ! !
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