src/Tools/jEdit/src/document_model.scala

                 (for ((_, model) <- st.buffer_models.iterator) yield model.node_name).toList
               val touched_nodes = model_edits.map(_._1)
               val pending_nodes = for ((node_name, None) <- purged) yield node_name
               (open_nodes ::: touched_nodes ::: pending_nodes).map((_, Position.none))
             }
-            val retain = PIDE.resources.dependencies(imports).names.toSet
+            val retain = PIDE.resources.dependencies(imports).theories.toSet
 
             for ((node_name, Some(edits)) <- purged; if !retain(node_name); edit <- edits)
               yield edit
           }
           else Nil