// get old web progress listener instance and dispose
Field f_Mozilla_webProgressListener = mozClass.getDeclaredField("webProgressListener");
f_Mozilla_webProgressListener.setAccessible(true);
final XPCOMObject oldWebProgressListener =
(XPCOMObject) f_Mozilla_webProgressListener.get(m_webBrowser);
oldWebProgressListener.dispose();
// get methods which needed to delegate to
final Method m_Mozilla_QueryInterface =
mozClass.getDeclaredMethod("QueryInterface", new Class[]{long.class, long.class});
final Method m_Mozilla_AddRef = mozClass.getDeclaredMethod("AddRef", new Class[0]);
final Method m_Mozilla_Release = mozClass.getDeclaredMethod("Release", new Class[0]);