--- a/HierarchicalFileList.st	Sun Jul 29 10:16:35 2018 +0200
+++ b/HierarchicalFileList.st	Sun Jul 29 10:18:22 2018 +0200
@@ -225,7 +225,7 @@
 !
 
 root:aRoot
-    self criticalDo:[
+    self synchronized:[
         indicatorList notNil ifTrue:[
             indicatorList do:[:el| el resetFetchIndicator ].
             indicatorList removeAll.
@@ -235,6 +235,8 @@
         self showRoot ifFalse:[aRoot setExpanded:true ]
     ].
     ^ super root:aRoot
+
+    "Modified: / 28-07-2018 / 15:48:43 / Claus Gittinger"
 ! !
 
 !HierarchicalFileList methodsFor:'actions'!
@@ -251,7 +253,7 @@
     matchBlock := aBlock.
 
     root notNil ifTrue:[
-        self criticalDo:[
+        self synchronized:[
             self stopMonitoringTask.
             root matchBlockChanged.
         ].
@@ -259,6 +261,7 @@
     ].
 
     "Modified: / 23-07-2018 / 13:24:06 / Stefan Vogel"
+    "Modified: / 28-07-2018 / 15:48:38 / Claus Gittinger"
 !
 
 sortBlock
@@ -287,8 +290,8 @@
 sortBlock:aBlock
     sortBlock := aBlock.
 
-    root notNil ifTrue:[
-        self criticalDo:[
+    self synchronized:[
+        root notNil ifTrue:[
             self stopMonitoringTask.
             root recursiveSort:aBlock.
         ].
@@ -296,6 +299,7 @@
     ].
 
     "Modified: / 23-07-2018 / 13:24:17 / Stefan Vogel"
+    "Modified: / 28-07-2018 / 15:48:54 / Claus Gittinger"
 ! !
 
 !HierarchicalFileList methodsFor:'private-monitoring task'!
@@ -454,9 +458,9 @@
 startIndicatorValidationFor:anItem
     "an item will be registered for an indication update"
 
-    |prio|
+    self synchronized:[
+        |prio|
 
-    self criticalDo:[
         indicatorList size == 0 ifTrue:[
             indicatorList := OrderedCollection new.
         ] ifFalse:[
@@ -479,17 +483,21 @@
             indicatorTask resume.
         ]
     ].
+
+    "Modified (format): / 28-07-2018 / 15:49:06 / Claus Gittinger"
 !
 
 stopIndicatorValidationFor:anItem
     "stop the indicator validation for an item"
 
-    self criticalDo:[
+    self synchronized:[
         indicatorList notNil ifTrue:[
             indicatorList removeIdentical:anItem ifAbsent:nil.
             anItem resetFetchIndicator.
         ]
     ].
+
+    "Modified: / 28-07-2018 / 15:49:15 / Claus Gittinger"
 !
 
 updateIndicatorCycle
@@ -505,7 +513,7 @@
 
     [ 
         [ task notNil ] whileTrue:[
-            self criticalDo:[
+            self synchronized:[
                 (     dependents    size ~~ 0       "/ no dependencies (stop task)
                  and:[indicatorList size ~~ 0]      "/ nothing to do
                 ) ifTrue:[
@@ -528,7 +536,7 @@
     ] ifCurtailed:[
         task notNil ifTrue:[
             "/ oops, process terminated
-            self criticalDo:[
+            self synchronized:[
                 "/ test whether a new task already started
                 indicatorTask == task ifTrue:[
                     indicatorTask := nil
@@ -538,6 +546,7 @@
     ].
 
     "Modified: / 27-02-2007 / 11:49:07 / cg"
+    "Modified: / 28-07-2018 / 15:51:30 / Claus Gittinger"
 ! !
 
 !HierarchicalFileList::HierarchicalFileItem class methodsFor:'instance creation'!
@@ -929,10 +938,12 @@
     model := self model.
     model isNil ifTrue:[ ^ nil ].
 
-    model criticalDo:[
+    model synchronized:[
         children isNil ifTrue:[ self readChildren ].
     ].
     ^ children
+
+    "Modified: / 28-07-2018 / 15:49:26 / Claus Gittinger"
 !
 
 icon
@@ -1384,7 +1395,7 @@
         ^ self
     ].
 
-    model criticalDo:[
+    model synchronized:[
         addedItems := OrderedCollection new:128.
         unusedDict := Dictionary new:size.
 
@@ -1412,6 +1423,7 @@
     ].
 
     "Modified (format): / 25-01-2018 / 12:03:40 / mawalch"
+    "Modified: / 28-07-2018 / 15:49:41 / Claus Gittinger"
 !
 
 updateList