add: retvals.files = null; 
context: function onCancel(){  // Close the window.  retvals.buttonStatus = nsIFilePicker.returnCancel;  retvals.file = null;  return true;}
meta: 5459	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5459/d73ec61a6799c808a7543ecb8ac3e83185fb8ec3/filepicker.js/buggy/xpfe/components/filepicker/res/content/filepicker.js