--- a/HierarchicalDropTargetController.st	Fri Dec 18 08:06:18 2015 +0100
+++ b/HierarchicalDropTargetController.st	Fri Dec 18 08:07:36 2015 +0100
@@ -197,7 +197,7 @@
     expandBlock notNil ifTrue:[
         Processor removeTimedBlock:expandBlock.
     ].
-    processEvents := (aLineOrNil isNil).
+    processEvents := aLineOrNil isNil.
     aDropContext contentsWillChange.
 
     (aLineOrNil isNil and:[highlightMode notNil]) ifTrue:[
@@ -236,6 +236,11 @@
     view paint:fgColor on:bgColor.
     item displayOn:view x:x0 y:y0 h:(y1 - y0) isHighlightedAsSelected:false.
 
+    view device isX11Platform ifTrue:[
+        "work around X11 draw problems"
+        Delay waitForMilliseconds:20.
+    ].
+
     item isExpanded ifTrue:[ ^ self ].
     item canExpand ifFalse:[ ^ self ].
 
@@ -266,6 +271,10 @@
     aDropContext saveDraw:[
         item expand.
         view windowGroup processExposeEvents.
+        view device isX11Platform ifTrue:[
+            "work around X11 draw problems"
+            Delay waitForMilliseconds:20.
+        ].
     ].
 ! !