--- a/Tools__NavigationState.st	Fri Feb 20 22:44:39 2015 +0100
+++ b/Tools__NavigationState.st	Fri Feb 20 22:46:26 2015 +0100
@@ -1113,7 +1113,9 @@
         ^ Tools::NewSystemBrowser bookmarkForClass:mth mclass selector:mth selector
     ].
     (cls := self theSingleSelectedClass) notNil ifTrue:[
-        ^ Tools::NewSystemBrowser bookmarkForClass:cls selector:nil
+        cls name notNil ifTrue:[
+            ^ Tools::NewSystemBrowser bookmarkForClass:cls selector:nil
+        ].
     ].
     ^ nil
 
@@ -1723,15 +1725,15 @@
 !NavigationState class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libtool/Tools__NavigationState.st,v 1.59 2015-02-19 12:19:27 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libtool/Tools__NavigationState.st,v 1.60 2015-02-20 21:46:26 cg Exp $'
 !
 
 version_CVS
-    ^ '$Header: /cvs/stx/stx/libtool/Tools__NavigationState.st,v 1.59 2015-02-19 12:19:27 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libtool/Tools__NavigationState.st,v 1.60 2015-02-20 21:46:26 cg Exp $'
 !
 
 version_SVN
-    ^ '$Id: Tools__NavigationState.st,v 1.59 2015-02-19 12:19:27 cg Exp $'
+    ^ '$Id: Tools__NavigationState.st,v 1.60 2015-02-20 21:46:26 cg Exp $'
 ! !