--- a/HierarchicalDropTargetController.st	Thu Jun 16 23:25:06 2016 +0200
+++ b/HierarchicalDropTargetController.st	Thu Jun 30 11:01:49 2016 +0200
@@ -196,6 +196,7 @@
 
     expandBlock notNil ifTrue:[
         Processor removeTimedBlock:expandBlock.
+        expandBlock := nil.
     ].
     processEvents := aLineOrNil isNil.
     aDropContext contentsWillChange.
@@ -252,9 +253,9 @@
             ^ self
         ].
     ].
-
+    expandBlock := [self expandForDrop:aDropContext at:aLineOrNil].
     Processor 
-        addTimedBlock: [self expandForDrop:aDropContext at:aLineOrNil]
+        addTimedBlock:expandBlock
         afterMilliseconds:(self class delayMilliSecondsBeforeExpand).
 !