add:  this.mLauncher.setWebProgressListener( null );  
context:     onCancel: function() {        // Cancel app launcher.        try {            this.mLauncher.Cancel();        } catch( exception ) {        }                // Unhook dialog from this object.        this.mDialog.dialog = null;        // Close up dialog by returning true.        return true;    },
meta: 5459	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5459/8b9240bcabf6fb058db16fbb472a864083f6f76b/nsHelperAppDlg.js/clean/embedding/components/ui/helperAppDlg/nsHelperAppDlg.js