diff -r ee0823ce2828 -r 10d608cc7470 src/Pure/Thy/thy_resources.scala
--- a/src/Pure/Thy/thy_resources.scala	Sun Nov 12 20:17:29 2017 +0100
+++ b/src/Pure/Thy/thy_resources.scala	Sun Nov 12 20:50:24 2017 +0100
@@ -48,6 +48,17 @@
     }
   }
 
+  class Session private[Thy_Resources](
+    options: Options, override val resources: Thy_Resources)
+    extends isabelle.Session(options, resources)
+  {
+    session =>
+
+    def load_theories(theories: List[(String, Position.T)],
+        qualifier: String = Sessions.DRAFT, master_dir: String = ""): List[Document.Node.Name] =
+      resources.load_theories(session, theories, qualifier = qualifier, master_dir = master_dir)
+  }
+
 
   /* internal state */