diff -r 4f264fdf8d0e -r 681447a9ffe5 src/Pure/PIDE/text.scala
--- a/src/Pure/PIDE/text.scala	Thu Aug 25 11:27:37 2011 +0200
+++ b/src/Pure/PIDE/text.scala	Thu Aug 25 11:41:48 2011 +0200
@@ -64,7 +64,7 @@
 
   object Perspective
   {
-    val empty = Perspective(Nil)
+    val empty: Perspective = Perspective(Nil)
 
     def apply(ranges: Seq[Range]): Perspective =
     {