add: UpdateTreeGrouping(); 
context:   observe: function(aPrefBranch, aTopic, aPrefName) {    try {      GroupBy(aPrefBranch.QueryInterface(Components.interfaces.nsIPrefBranch).getCharPref(aPrefName));    }    catch(ex) {    }  }
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/d89efd3567fab9baa3b9c6db18958ab1998f4ba4/history.js/clean/xpfe/components/history/resources/history.js