--- a/src/Pure/PIDE/markup_tree.scala Thu Jun 23 14:48:32 2011 +0200
+++ b/src/Pure/PIDE/markup_tree.scala Thu Jun 23 14:52:32 2011 +0200
@@ -7,7 +7,7 @@
package isabelle
-
+import java.lang.System
import javax.swing.tree.DefaultMutableTreeNode
import scala.collection.immutable.SortedMap