diff -r 1a9f569b5b7e -r c3dbaa155ece src/Pure/GUI/wrap_panel.scala
--- a/src/Pure/GUI/wrap_panel.scala	Tue Apr 01 22:25:01 2014 +0200
+++ b/src/Pure/GUI/wrap_panel.scala	Tue Apr 01 23:04:22 2014 +0200
@@ -62,7 +62,7 @@
         }
 
         for {
-          i <- 0 until target.getComponentCount
+          i <- (0 until target.getComponentCount).iterator
           m = target.getComponent(i)
           if m.isVisible
           d = if (preferred) m.getPreferredSize else m.getMinimumSize()