diff -r a2b8c3d31037 -r f826ba18fe08 src/Pure/Thy/html.scala
--- a/src/Pure/Thy/html.scala	Thu Jun 08 13:17:40 2017 +0200
+++ b/src/Pure/Thy/html.scala	Thu Jun 08 14:08:07 2017 +0200
@@ -193,7 +193,8 @@
   def image(src: String, alt: String = ""): XML.Elem =
     XML.Elem(Markup("img", List("src" -> src) ::: proper_string(alt).map("alt" -> _).toList), Nil)
 
-  def source(src: String): XML.Elem = pre("source", text(src))
+  def source(body: XML.Body): XML.Elem = pre("source", body)
+  def source(src: String): XML.Elem = source(text(src))
 
   def style(s: String): XML.Elem = XML.elem("style", text(s))