src/Tools/jEdit/src/plugin.scala

           val thys =
             for {
               buffer <- buffers
               model <- PIDE.document_model(buffer)
               if model.is_theory
-            } yield model.node_name
+            } yield (model.node_name, Position.none)
 
           val thy_info = new Thy_Info(PIDE.thy_load)
           // FIXME avoid I/O in Swing thread!?!
           val files = thy_info.dependencies(thys).deps.map(_.name.node).
             filter(file => !loaded_buffer(file) && PIDE.thy_load.check_file(view, file))