when running javawebstart on the system for the first time, our java code is suppose to look for the mozilla prefs.js file, and set the following line:

user_pref("browser.helperApps.neverAsk.openFile", "application%2Fx-java-jnlp-file");

it is working on unix only; on windows the look up code to find the path to prefs.js seems to be broken