--- a/Tools__ClassCategoryList.st	Wed Nov 19 22:41:47 2014 +0100
+++ b/Tools__ClassCategoryList.st	Wed Nov 19 23:04:26 2014 +0100
@@ -306,6 +306,13 @@
             class isBehavior ifFalse:[ 
                 self breakPoint: #jv.
             ] ifTrue:[
+                listValid == false ifTrue:[
+                    ^ self
+                ].
+                self window sensor userEventCount > 100 ifTrue:[
+                    self invalidateList.
+                    ^ self
+                ].
                 self enqueueDelayedUpdate:#updateCategoryForChangedMethod with:class from:self.
             ].
              ^ self.
@@ -1153,10 +1160,10 @@
 !ClassCategoryList class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libtool/Tools__ClassCategoryList.st,v 1.57 2014-11-19 21:41:26 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libtool/Tools__ClassCategoryList.st,v 1.58 2014-11-19 22:04:26 cg Exp $'
 !
 
 version_CVS
-    ^ '$Header: /cvs/stx/stx/libtool/Tools__ClassCategoryList.st,v 1.57 2014-11-19 21:41:26 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libtool/Tools__ClassCategoryList.st,v 1.58 2014-11-19 22:04:26 cg Exp $'
 ! !