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: 5459	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5459/c44a73e5d90980a4e4134ab426cad23114c14e9f/nsPrefWindow.js/clean/suite/common/pref/nsPrefWindow.js