diff -r bc71778a327d -r 8e743ca417b9 src/Pure/Thy/html.scala
--- a/src/Pure/Thy/html.scala	Wed Dec 09 21:55:14 2009 +0100
+++ b/src/Pure/Thy/html.scala	Thu Dec 10 13:43:51 2009 +0100
@@ -34,7 +34,8 @@
 
   def spans(tree: XML.Tree): List[XML.Tree] =
     tree match {
-      case XML.Elem(name, _, ts) => List(span(name, ts.flatMap(spans)))
+      case XML.Elem(name, _, ts) =>
+        List(XML.elem(Markup.DATA, List(tree, span(name, ts.flatMap(spans)))))
       case XML.Text(txt) =>
         val ts = new ListBuffer[XML.Tree]
         val t = new StringBuilder