--- a/AbstractHierarchicalItem.st	Mon Jul 30 14:28:14 2018 +0200
+++ b/AbstractHierarchicalItem.st	Mon Jul 30 14:28:50 2018 +0200
@@ -959,19 +959,22 @@
     "
     |model|
 
-    what ~~ #redraw ifTrue:[
-        (what ~~ #hierarchy and:[what ~~ #icon]) ifTrue:[
-            self class doResetExtentOnChange ifTrue:[
-                self makeWidthAndHeightUnknown
-            ].
+    (what ~~ #redraw 
+     and:[what ~~ #hierarchy 
+     and:[what ~~ #icon 
+     and:[self class doResetExtentOnChange]]]) ifTrue:[
+        self makeWidthAndHeightUnknown
+    ].
+
+    (model := self model) notNil ifTrue:[
+        model synchronized:[
+            model itemChanged:what with:anArgument from:self.
         ].
     ].
-    (model := self model) notNil ifTrue:[
-        model itemChanged:what with:anArgument from:self
-    ].
     super changed:what with:anArgument
 
     "Modified: / 24-11-2010 / 17:21:20 / cg"
+    "Modified: / 30-07-2018 / 14:25:45 / Stefan Vogel"
 !
 
 childrenOrderChanged