rem: var pbi = pref.QueryInterface(Components.interfaces.nsIPrefBranchInternal); 
add: var pbi = pref.QueryInterface(Components.interfaces.nsIPrefBranch2); 
context:   startup: function(prefName)  {    this.domain = prefName;    try {      var pbi = pref.QueryInterface(Components.interfaces.nsIPrefBranchInternal);      pbi.addObserver(this.domain, this, false);    } catch(ex) {      dump("Failed to observe prefs: " + ex + "\n");    }  },
meta: 10234	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/10234/361daac9367ad464688c4da3c3206d18cb2ae94e/editor.js/buggy/editor/ui/composer/content/editor.js