--- a/extensions.st	Tue May 15 18:16:27 2018 +0200
+++ b/extensions.st	Wed May 16 15:38:40 2018 +0200
@@ -78,13 +78,14 @@
 historyManagerSignature
     "the signature added by the history manager"
 
-    ^self historyManagerSignatures
-        at: (Array with: OperatingSystem getHostName with: OperatingSystem getLoginName)
-        ifAbsent: [OperatingSystem getLoginName]
+    ^ (self historyManagerSignatures
+            at:{OperatingSystem getHostName. OperatingSystem getLoginName}
+            ifAbsent:nil) ? OperatingSystem getFullUserName.
 
     "Created: / 04-10-2008 / 12:06:58 / Jan Vrany <vranyj1@fel.cvut.cz>"
     "Modified: / 08-07-2011 / 10:24:48 / Jan Vrany <jan.vrany@fit.cvut.cz>"
     "Modified: / 04-08-2011 / 17:24:21 / cg"
+    "Modified: / 16-05-2018 / 14:21:34 / Stefan Vogel"
 ! !
 
 !UserPreferences methodsFor:'accessing-prefs-changes & history'!
@@ -92,12 +93,19 @@
 historyManagerSignature: aString
     "the signature added by the history manager"
 
-    ^self historyManagerSignatures
-        at: (Array with: OperatingSystem getHostName with: OperatingSystem getLoginName)
-        put: aString
+    aString isEmptyOrNil ifTrue:[
+        self historyManagerSignatures 
+                removeKey:{OperatingSystem getHostName. OperatingSystem getLoginName}
+                ifAbsent:[].
+        ^ aString.
+    ].
+
+    ^ self historyManagerSignatures
+        at:{OperatingSystem getHostName. 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"
+    "Modified: / 16-05-2018 / 14:18:41 / Stefan Vogel"
 ! !
 
 !UserPreferences methodsFor:'accessing-prefs-changes & history'!