diff -r bf08bd96d408 -r a6f807104d8e rt/vm/src/test/java/org/apidesign/vm4brwsr/ImplementExternalInterfaceTest.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rt/vm/src/test/java/org/apidesign/vm4brwsr/ImplementExternalInterfaceTest.java	Wed May 28 13:38:29 2014 +0200
@@ -0,0 +1,58 @@
+/**
+ * Back 2 Browser Bytecode Translator
+ * Copyright (C) 2012 Jaroslav Tulach <jaroslav.tulach@apidesign.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. Look for COPYING file in the top folder.
+ * If not, see http://opensource.org/licenses/GPL-2.0.
+ */
+package org.apidesign.vm4brwsr;
+
+import javax.script.ScriptEngine;
+import org.testng.annotations.AfterClass;
+import org.testng.annotations.BeforeClass;
+import org.testng.annotations.Test;
+
+/** Tests whether private impl can implement public interface method
+ * from another extension.
+ *
+ * @author Jaroslav Tulach <jtulach@netbeans.org>
+ */
+public class ImplementExternalInterfaceTest {
+    @Test public void checkHello() throws Exception {
+        String exp = "Hello!";
+        
+        code.assertExec("Can extension implement class from another extension",
+            ImplementFactory.class, "hello__Ljava_lang_String_2", 
+            exp
+        );
+    }
+
+    private static TestVM code;
+    
+    @BeforeClass 
+    public static void compileTheCode() throws Exception {
+        StringBuilder sb = new StringBuilder();
+        ScriptEngine[] eng = { null };
+        code = TestVM.compileClassAsExtension(sb, eng, 
+            "org/apidesign/vm4brwsr/ImplementInterface", null, null
+        );
+        code = TestVM.compileClassesAsExtension(sb, eng, null, null,
+            "org/apidesign/vm4brwsr/ImplementFactory", 
+            "org/apidesign/vm4brwsr/ImplementFactory$Impl"
+        );
+    }
+    @AfterClass
+    public static void releaseTheCode() {
+        code = null;
+    }
+}