src/Pure/System/gui.scala

--- a/src/Pure/System/gui.scala	Sat Sep 07 11:28:30 2013 +0200
+++ b/src/Pure/System/gui.scala	Sat Sep 07 11:36:03 2013 +0200
@@ -114,7 +114,7 @@
   /* icon */
 
   def isabelle_icon(): ImageIcon =
-    new ImageIcon(Isabelle_System.platform_path(Path.explode("~~/lib/logo/isabelle.gif")))
+    new ImageIcon(getClass.getClassLoader.getResource("isabelle/isabelle.gif"))
 
   def isabelle_image(): Image = isabelle_icon().getImage
 }