add:  return true; 
context:       onCancel:        function ()          {            for( var i = 0; i < hPrefWindow.cancelHandlers.length; i++ )              try {                hPrefWindow.cancelHandlers[i]();              } catch (e) {                dump("some silly cancel handler /*"+hPrefWindow.cancelHandlers[i]+"*/ failed: "+ e);              }          },
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/89c87c04944876b287d29e996b24d788baa5a5c2/nsPrefWindow.js/buggy/xpfe/components/prefwindow/resources/content/nsPrefWindow.js