rem: var prefBranch = prefService.getBranch(null).QueryInterface(Components.interfaces.nsIPrefBranchInternal); 
add: var prefBranch = prefService.getBranch(null).QueryInterface(Components.interfaces.nsIPrefBranch2); 
context: function AddPrefObservers(){  var prefService = Components.classes["@mozilla.org/preferences-service;1"]                              .getService(Components.interfaces.nsIPrefService);  var prefBranch = prefService.getBranch(null).QueryInterface(Components.interfaces.nsIPrefBranchInternal);  prefBranch.addObserver(kPrefMailAddrBookLastNameFirst, gMailAddrBookLastNameFirstObserver, false);}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/4b68fa447a8983137138e2d20be274a6c51fc137/addressbook.js/clean/mailnews/addrbook/resources/content/addressbook.js