The current Java Plug-In contains custom native code (on Windows) for supporting roaming user profiles. Need to incorporate this into the browser-side code and feed value of user.home to applet sub-process. Need to revisit current code and use of Config class to make sure it is working properly.
Also need to check the capturing of the USER_JPI_PROFILE environment variable from CJavaJNI.cpp and the sending of this value up to Java via the javaplugin.user.profile system property in the old Java Plug-In. Apparently the Config class looks for this system property.