src/Pure/Thy/file_format.scala

--- a/src/Pure/Thy/file_format.scala	Sat Dec 19 12:05:17 2020 +0100
+++ b/src/Pure/Thy/file_format.scala	Sat Dec 19 15:14:01 2020 +0100
@@ -89,7 +89,7 @@
     } yield s
   }
 
-  def make_preview(snapshot: Document.Snapshot): Option[Presentation.Preview] = None
+  def html_document(snapshot: Document.Snapshot): Option[Presentation.HTML_Document] = None
 
 
   /* PIDE session agent */