JSObject fails in Firefox extensions

FULL PRODUCT VERSION :
Java(TM) SE Runtime Environment (build 1.6.0_13-b03)

ADDITIONAL OS VERSION INFORMATION :
Ubuntu 8.10

EXTRA RELEVANT SYSTEM CONFIGURATION :
Firefox 3.0.8
Java(TM) Plug-in 1.6.0_13-b03

A DESCRIPTION OF THE PROBLEM :
JSObject fails in Firefox extensions. Calls to getWindow generate an error and calling .setMember on a JSObject have no effect.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Install Firefox 3.0.8
Install Java Plugin
Install test case into Firefox (failcase-1.0.xpi)

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The Java code to successfully execute without error.
ACTUAL -
Calls to getWindow generate this error
 java.security.PrivilegedActionException: java.security.PrivilegedActionException: java.lang.reflect.InvocationTargetException

setMember has no effect.


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
Calling the following Java code from a Firefox extension demonstrates the issue.
    public void test_get_window() {
        JSObject.getWindow(this);
    }

    public JSObject test_set_member(JSObject js) {
        js.setMember("msg", "bye");
        return js;
    }

Firefox extension test case attached seperatly.


Unzip the .xpi to see the files inside.
---------- END SOURCE ----------