src/Tools/jEdit/src/scala_console.scala

   private case class Execute(console: Console, out: Output, err: Output, command: String)
     extends Request
 
   private class Interpreter
   {
-    private val running = Synchronized(None: Option[Thread])
+    private val running = Synchronized[Option[Thread]](None)
     def interrupt { running.change(opt => { opt.foreach(_.interrupt); opt }) }
 
     private val settings = new GenericRunnerSettings(report_error)
     settings.classpath.value = reconstruct_classpath()