src/Tools/jEdit/src/plugin.scala

                     "Isabelle Syslog", Library.scrollable_text(Isabelle.session.current_syslog()))
               }
 
             case Session.Ready =>
               Isabelle.jedit_buffers.foreach(Isabelle.init_model)
-              delay_load(true)
+              Swing_Thread.later { delay_load.invoke() }
 
             case Session.Shutdown =>
               Isabelle.jedit_buffers.foreach(Isabelle.exit_model)
-              delay_load(false)
+              Swing_Thread.later { delay_load.revoke() }
 
             case _ =>
           }
         case bad => System.err.println("session_manager: ignoring bad message " + bad)
       }

         case msg: BufferUpdate
         if msg.getWhat == BufferUpdate.LOADED || msg.getWhat == BufferUpdate.PROPERTIES_CHANGED =>
           if (Isabelle.session.is_ready) {
             val buffer = msg.getBuffer
             if (buffer != null && !buffer.isLoading) Isabelle.init_model(buffer)
-            delay_load(true)
+            Swing_Thread.later { delay_load.invoke() }
           }
 
         case msg: EditPaneUpdate
         if (msg.getWhat == EditPaneUpdate.BUFFER_CHANGING ||
             msg.getWhat == EditPaneUpdate.BUFFER_CHANGED ||