[Bug 369620] (when pref mailnews.thread_pane_column_unthreads=true):

Threading via column header forces Sort by "Order Received", should be "Date"

Patch by bienvenu, sr=mscott

mailnews/base/resources/content/threadPane.js

@@ -294,7 +294,7 @@ function MsgSortByThread()
     return;
   dbview.viewFlags |= nsMsgViewFlagsType.kThreadedDisplay;
   dbview.viewFlags &= ~nsMsgViewFlagsType.kGroupBySort;
-  MsgSortThreadPane(nsMsgViewSortType.byId);
+  MsgSortThreadPane(nsMsgViewSortType.byDate);
 }
 
 function MsgSortThreadPane(sortType)