Comment 9 for bug 25830

http://screaming.org/~pohl/ServletWithCache.java

The above link should be a suitable example. As for where the function should
be, my instincts led me to the
Edit-->Preferences-->Navigator-->HelperApplications where I attempted to add a
mapping for ".java" of type text/x-java. In the panel where you "add" or "edit"
the mapping, I would imagine that there would be a checkbox (for text/* types)
that says "display within browser window", and perhaps checking this checkbox
would also disable the widgets for selecting the helper application.