src/Pure/General/file_watcher.scala

--- a/src/Pure/General/file_watcher.scala	Mon Apr 06 12:36:00 2020 +0200
+++ b/src/Pure/General/file_watcher.scala	Mon Apr 06 12:53:45 2020 +0200
@@ -84,7 +84,7 @@
 
     /* changed directory entries */
 
-    private val delay_changed = Isabelle_Thread.delay_last(delay)
+    private val delay_changed = Delay.last(delay)
     {
       val changed = state.change_result(st => (st.changed, st.copy(changed = Set.empty)))
       handle(changed)