src/Pure/System/gui_setup.scala

--- a/src/Pure/System/gui_setup.scala	Sat Jan 12 21:15:44 2013 +0100
+++ b/src/Pure/System/gui_setup.scala	Sat Jan 12 22:08:38 2013 +0100
@@ -23,6 +23,8 @@
   }
 
   def top = new MainFrame {
+    iconImage = Isabelle_System.get_icon().getImage
+
     title = "Isabelle setup"
 
     // components