rem: this.mPrefs.addObserver(aDomain, aFunction); 
add: var pbi = XPCU.QI(this.mPrefs, "nsIPrefBranchInternal"); if (pbi) pbi.addObserver(aDomain, aFunction, false); 
context:   addObserver: function(aDomain, aFunction)  {    if (!this.mPrefs) this.init();    this.mPrefs.addObserver(aDomain, aFunction);  },
meta: 8395	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/8395/8403e03f3bdc8feaf5cc5f31884e180a04c93a26/PrefUtils.js/clean/extensions/inspector/resources/content/jsutil/system/PrefUtils.js