--- a/src/Pure/GUI/swing_thread.scala Thu Feb 20 14:17:28 2014 +0100
+++ b/src/Pure/GUI/swing_thread.scala Thu Feb 20 14:36:17 2014 +0100
@@ -7,6 +7,7 @@
package isabelle
+
import javax.swing.{SwingUtilities, Timer}
import java.awt.event.{ActionListener, ActionEvent}