src/Pure/System/isabelle_process.scala

--- a/src/Pure/System/isabelle_process.scala	Tue Apr 09 20:16:52 2013 +0200
+++ b/src/Pure/System/isabelle_process.scala	Tue Apr 09 20:27:27 2013 +0200
@@ -97,8 +97,7 @@
     else {
       val main = XML.Elem(Markup(kind, props), Protocol.clean_message(body))
       val reports = Protocol.message_reports(props, body)
-      for (msg <- main :: reports)
-        receiver(new Output(xml_cache.cache_tree(msg).asInstanceOf[XML.Elem]))
+      for (msg <- main :: reports) receiver(new Output(xml_cache.elem(msg)))
     }
   }