src/Pure/PIDE/resources.scala

--- a/src/Pure/PIDE/resources.scala	Sat Aug 18 13:52:12 2018 +0200
+++ b/src/Pure/PIDE/resources.scala	Sat Aug 18 14:16:24 2018 +0200
@@ -194,9 +194,6 @@
     else Some(Document.Node.Header(imports.map((_, Position.none))))
   }
 
-  def is_hidden(name: Document.Node.Name): Boolean =
-    !name.is_theory || name.theory == Sessions.root_name || name.is_bibtex_theory
-
 
   /* blobs */