The issue is stated inside the bug 6349480.
The bug 6349480 has been already fixed but
I could still reproducible the problem.

> uname -a
Linux flambeau 2.4.29 #6 Thu Jan 20 16:30:37 PST 2005 i686 unknown unknown GNU/Linux

> java -version
java version "1.7.0-ea"
Java(TM) SE Runtime Environment (build 1.7.0-ea-b07)
Java HotSpot(TM) Client VM (build 1.7.0-ea-b07, mixed mode)

I reproduced it on GNOME 2.6.2 / Metacity.