(function(){
　var searchbar = BrowserSearch.searchBar;
　if (searchbar){
　　searchbar.handleSearchCommand_original = searchbar.handleSearchCommand;
　　searchbar.handleSearchCommand = function(aEvent){
　　　this.handleSearchCommand_original(aEvent);
　　　　this.value = "";
　　　setTimeout(function(){
　　　　var ss = Cc['@mozilla.org/browser/search-service;1'].getService(Ci.nsIBrowserSearchService);
　　　　ss.currentEngine = ss.defaultEngine;
　　　}, 0);
　　};
　}
})();