java app is not getting input from keyboard

Binary package hint: firefox

The java crossword app (http://blogs.wsj.com/puzzle/2010/08/05/pin-numbers-crossword/) appears to have been loaded successfully, but none of the keystroke that I enter is recognized.

The release of Ubuntu that I am using is Ubuntu 10.04.1 LTS.
The firefox package that I am using is 3.6.8+build1+nobinonly-0ubuntu0.10.04.1

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: firefox 3.6.8+build1+nobinonly-0ubuntu0.10.04.1
ProcVersionSignature: Ubuntu 2.6.32-24.39-generic 2.6.32.15+drm33.5
Uname: Linux 2.6.32-24-generic i686
Architecture: i386
CheckboxSubmission: f2f47b0c3d1967572ad6aa2c8f854fb9
CheckboxSystem: 0531969bcfd4f03af7405c98dc94a948
Date: Mon Aug 9 11:10:03 2010
FirefoxPackages:
 firefox 3.6.8+build1+nobinonly-0ubuntu0.10.04.1
 firefox-gnome-support 3.6.8+build1+nobinonly-0ubuntu0.10.04.1
 firefox-branding 3.6.8+build1+nobinonly-0ubuntu0.10.04.1
 abroswer N/A
 abrowser-branding N/A
InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release i386 (20091028.5)
ProcEnviron:
 PATH=(custom, user)
 LANG=en_HK.utf8
 SHELL=/bin/bash
SourcePackage: firefox