rem: var str = Components.classes["@mozilla.org/supports-wstring;1"] .createInstance(Components.interfaces.nsISupportsWString); 
add: var str = Components.classes["@mozilla.org/supports-string;1"] .createInstance(Components.interfaces.nsISupportsString); 
context:   setUnicharPref: function (aPrefName, aPrefValue)    {      try        {          var str = Components.classes["@mozilla.org/supports-wstring;1"]                              .createInstance(Components.interfaces.nsISupportsWString);          str.data = aPrefValue;          this.mPrefService.setComplexValue(aPrefName,                                            Components.interfaces.nsISupportsWString, str);        }      catch(e)        {        }    },
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/3703f3c61bce0c45d03ff380dc6b806f944ecb73/nsUserSettings.js/buggy/xpfe/global/resources/content/nsUserSettings.js