src/Pure/PIDE/document.scala

--- a/src/Pure/PIDE/document.scala	Thu Sep 01 16:58:41 2011 +0200
+++ b/src/Pure/PIDE/document.scala	Thu Sep 01 22:29:57 2011 +0200
@@ -47,6 +47,7 @@
           case other: Name => node == other.node
           case _ => false
         }
+      override def toString: String = theory
     }
 
     sealed abstract class Edit[A, B]