add: } catch (e) { debug("some silly cancel handler /*"+hPrefWindow.cancelHandlers[i]+"*/ failed: "+ e); 
context:       onCancel:        function ()          {            for( var i = 0; i < hPrefWindow.cancelHandlers.length; i++ )              {                hPrefWindow.cancelHandlers[i]();              }          },
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/3321310f57ad13dcf5fba31de62da5e035cff1fe/nsPrefWindow.js/buggy/xpfe/components/prefwindow/resources/content/nsPrefWindow.js