diff -r 156c822f181a -r df80747342cb src/Pure/System/session.scala
--- a/src/Pure/System/session.scala	Sat Jun 25 19:38:35 2011 +0200
+++ b/src/Pure/System/session.scala	Sat Jun 25 20:03:07 2011 +0200
@@ -129,6 +129,7 @@
     _phase = new_phase
     phase_changed.event(new_phase)
   }
+  def is_ready: Boolean = phase == Session.Ready
 
   private val global_state = new Volatile(Document.State.init)
   def current_state(): Document.State = global_state.peek()