diff -r 50ab1db5c0fd -r 335750d989a3 src/Pure/PIDE/document.scala
--- a/src/Pure/PIDE/document.scala	Wed Jul 23 14:50:20 2014 +0200
+++ b/src/Pure/PIDE/document.scala	Wed Jul 23 15:00:46 2014 +0200
@@ -296,6 +296,9 @@
     def apply(name: Node.Name): Node =
       graph.default_node(name, Node.empty).get_node(name)
 
+    def is_maximal(name: Node.Name): Boolean =
+      graph.default_node(name, Node.empty).is_maximal(name)
+
     def + (entry: (Node.Name, Node)): Nodes =
     {
       val (name, node) = entry