diff -r 4ae766848ce0 -r 2fee889b9830 launcher/fx/src/main/java/org/apidesign/bck2brwsr/launcher/fximpl/JsClassLoader.java
--- a/launcher/fx/src/main/java/org/apidesign/bck2brwsr/launcher/fximpl/JsClassLoader.java	Mon Jun 17 16:17:46 2013 +0200
+++ b/launcher/fx/src/main/java/org/apidesign/bck2brwsr/launcher/fximpl/JsClassLoader.java	Mon Jun 17 17:40:30 2013 +0200
@@ -51,6 +51,21 @@
 
     @Override
     protected Class<?> findClass(String name) throws ClassNotFoundException {
+        if (name.startsWith("javafx")) {
+            return Class.forName(name);
+        }
+        if (name.startsWith("netscape")) {
+            return Class.forName(name);
+        }
+        if (name.startsWith("com.sun")) {
+            return Class.forName(name);
+        }
+        if (name.equals(JsClassLoader.class.getName())) {
+            return JsClassLoader.class;
+        }
+        if (name.equals(Fn.class.getName())) {
+            return Fn.class;
+        }
         URL u = findResource(name.replace('.', '/') + ".class");
         if (u != null) {
             InputStream is = null;