rem: var pbi = pb.QueryInterface(Components.interfaces.nsIPrefBranchInternal); 
add: var pbi = pb.QueryInterface(Components.interfaces.nsIPrefBranch2); 
context: function HistoryPanelUnload(){  var pb = Components.classes["@mozilla.org/preferences-service;1"].getService(Components.interfaces.nsIPrefBranch);  var pbi = pb.QueryInterface(Components.interfaces.nsIPrefBranchInternal);  pbi.removeObserver("browser.history.grouping", groupObserver, false);}
meta: 5872	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5872/95797b8d9069faeb422c1d2cd0492f1df563177e/history.js/clean/suite/common/history/history.js