src/Pure/PIDE/text.scala

   {
     val empty: Perspective = Perspective(Nil)
 
     def full: Perspective = Perspective(List(Range.full))
 
-    def apply(ranges: Seq[Range]): Perspective =
+    def apply(ranges: List[Range]): Perspective =
     {
       val result = new mutable.ListBuffer[Range]
       var last: Option[Range] = None
       def ship(next: Option[Range]) { result ++= last; last = next }