diff -r e1fff67b23ac -r 5d9693c2337e src/Pure/System/session.scala
--- a/src/Pure/System/session.scala	Sat Jun 18 17:32:13 2011 +0200
+++ b/src/Pure/System/session.scala	Sat Jun 18 17:33:27 2011 +0200
@@ -31,7 +31,7 @@
 }
 
 
-class Session(system: Isabelle_System)
+class Session(val system: Isabelle_System)
 {
   /* real time parameters */  // FIXME properties or settings (!?)