Java (1.6.0_24) with Firefox 4 on MacOSX fails to get component LocationOnScreen

Question

On MacOSX, with Java 1.6.0_24 (or _22), with Firefox 4, the method getLocationOnScreen() fails to get the right coordinate of an applet.
The returned value changes each time the mouse leaves/enters inside the applet.
This can be tested by deploying an applet with the given code (cf below)
and move the mouse outside/inside the applet.
Its not working with Firefox 4.0.
Java Plug-in 1.6.0_24
Using JRE version 1.6.0_24-b07-334-10M3326 Java HotSpot(TM) 64-Bit Server VM
(the 32bit mode is never activated even if it's checked in the application "get info" panel)
It's working fine with Firefox 3.6.15.
Java Plug-in 1.6.0_24
Using JRE version 1.6.0_24-b07-334-10M3326 Java HotSpot(TM) Client VM
import javax.swing.JApplet;
public class MyApplet extends JApplet
@Override public void start()
Thread t = new Thread()
public void run()
while (true)
System.out.println("Loc : " + MyApplet.this.getLocationOnScreen());
try
sleep(500);
catch (InterruptedException e)
e.printStackTrace();
t.start();
}

Answer 1

May it be downloading once without port specification and once with it?
What about 304? Could it be asking for http://localhost:80/xxx and being redirected to http://localhost/xxx (or viceversa)?
JWS identifies files based on exact URL so the one file without port spec is definitively different from the one without.I removed port 80 from applet tag's @jnlp_href, and now I only have one copy in the cache viewer, so thanks for the suggestion!
When I had 2 copies in the cache viewer, they both had identical jnlp files .. neither jnlp specified the port
Also, my jnlp on the server uses @codebase="$$codebase". I see now that the servlet never appends a port number if it is http port 80.
Anyway, now Web Start makes the following requests:
"GET /docx4all/application/applet2.jnlp HTTP/1.1" 200 3725
"GET /docx4all/application/docx4all.jar HTTP/1.1" 200 245142
"GET /docx4all/application/applet2.jnlp HTTP/1.1" 304 -
"GET /docx4all/application/docx4all.jar HTTP/1.1" 304 -
which is much better.
Now it just remains to work out how much of:
<offline-allowed/>
<shortcut online="false">
<desktop/>
<menu submenu="docx4all"/>
</shortcut>
<update check="background" policy="prompt-update" />
I can put back into my jnlp and still have @download="lazy" worked properly
cheers
Jason