return aHandlerApp.executable && aHandlerApp.executable.exists() && aHandlerApp.executable.isExecutable(); 
return this._isValidHandlerExecutable(aHandlerApp.executable); 
  isValidHandlerApp: function(aHandlerApp) {    if (!aHandlerApp)      return false;    if (aHandlerApp instanceof Ci.nsILocalHandlerApp)      return aHandlerApp.executable &&             aHandlerApp.executable.exists() &&             aHandlerApp.executable.isExecutable();    if (aHandlerApp instanceof Ci.nsIWebHandlerApp)      return aHandlerApp.uriTemplate;    if (aHandlerApp instanceof Ci.nsIWebContentHandlerInfo)      return aHandlerApp.uri;    return false;  },
5872	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/5872/16fe1c10ed03ade95659ef73edd0d82b7a324c4d/applications.js/buggy/browser/components/preferences/applications.js