I was trying to use tcgui, like from this howtoforge guide. The tcgui program, doesn't work on icedtea, not sure why. One solution was to remove it.
Another is assuming that you have a sun-jre. Is by running this command, in terminal:
sudo update-java-alternative -s java-6-sunTo check whether you have the jre from sun
update-java-alternative -lthis will list out the jre, that is available. When you see, "java-6-sun", then you have it.
p.s This I assume that you install java from repository, because not sure whether it will work if you install manually.