diff --git a/mailnews/base/resources/content/threadPane.xul b/mailnews/base/resources/content/threadPane.xul
index 11d81f4a8654..56d997b8722c 100644
--- a/mailnews/base/resources/content/threadPane.xul
+++ b/mailnews/base/resources/content/threadPane.xul
@@ -37,7 +37,6 @@ Rights Reserved.
 	  		  onselect="top.ThreadPaneSelectionChange(); document.commandDispatcher.updateCommands('tree-select');"
               onclick="ThreadPaneOnClick(event);"
               onblur="goOnEvent(this,'blur')"
-   	          ondragover="return DragOverTree(event);"
               ondraggesture="return BeginDragThreadTree(event);"
               ondragdrop="return DropOnThreadTree(event);"
               containment="http://home.netscape.com/NC-rdf#MessageChild"