Short desc:
  "no opt-out" mixed code unittests ( plugin and javaws cases, looks like the same issue )
  misses expected security exception in case of enabling mixed code protection options in
  Java CPL on Unix ( Solaris 10 sparc + FF 3.5 , RHEL 5.4 x86 + FF 3.5 ).
  Additional condition: during execution or in JCPL mixed code execution is NOT blocked.

  In opposite, on windows the same cases got security exception as expected, so additional security restrictions wok as expected.

See details in comments section.