Hi,
I am trying to call a method in the Ext.extend from FeedWindow.superclass.constructor.call().
I tried to call using this.markInvalid, Ext.markInvalid etc and all caused errors.
I am a novice to extJS and JS OOPs. Can anyone help me to resolve this issue and call those functions.

The code I have are,
-----------------------------

Code:
     FeedWindow.superclass.constructor.call(this, {
        title: 'Add Feed',
        iconCls: 'feed-icon',
        id: 'add-feed-win',
        autoHeight: true,
        width: 500,
        resizable: false,
        plain:true,
        modal: true,
        y: 100,
        autoScroll: true,
        closeAction: 'hide',
        height: 'auto',
        items: this.form,
        buttons:[{
            text: 'Add Feed!',
            handler: function() {
                this.form.getForm().submit({
                    url: $baseUrl+'feed-proxy.php',
                    success: function(){
                        this.validateFeed;
                    },
                    failure: function(){
                        this.markInvalid,
                    }
                });
            },
            scope: this
        },{
            text: 'Cancel',
            handler: this.hide.createDelegate(this, [])
        }],        
    });
--------------------------------------------------
Code:
 Ext.extend(FeedWindow, Ext.Window, {
    defaultFeeds : [
        ['http://www.divergingpath.com/rss.cfm?mode=full', 'Aaron Conran\'s Blog'],
        ['http://feeds.yuiblog.com/YahooUserInterfaceBlog',  'Yahoo! UI Blog'],
        ['http://feeds.feedburner.com/jquery/', 'jQuery Blog'],
        ['http://sports.yahoo.com/nba/rss.xml', 'NBA News'],
        ['http://feeds.dzone.com/dzone/frontpage', 'DZone.com']
    ],

    show : function(){
        if(this.rendered){
            this.feedUrl.setValue('');
        }
        FeedWindow.superclass.show.apply(this, arguments);
    },

    markInvalid : function(){
        this.feedUrl.markInvalid('The URL specified is not a valid RSS2 feed.');
        this.el.unmask();
    },

    validateFeed : function(response, options){
        var dq = Ext.DomQuery;
        var url = options.feedUrl;

        try{
            var xml = response.responseXML;
            var channel = xml.getElementsByTagName('channel')[0];
            var text;// = dq.selectValue('title', channel, url);
                
                // Add feed list in feed panel from the database
                Ext.Ajax.request({
                    url : $baseUrl+'feed_panel.php' ,
                    params : { action : 'newfeed', newUrl : url },
                    method: 'POST',
                    scope: this,
                    success: function ( result, request ) {                      
                        var stringData = result.responseText;                        
                        if(channel){
                            // var description = dq.selectValue('description', channel, 'No description available.');
                            this.el.unmask();
                            this.hide();
                            return this.fireEvent('validfeed', {
                                url: url,
                                text: result.responseText,
                            });
                        }        
                        
                    },
                    failure: function ( result, request) { 
                        Ext.MessageBox.alert('Failed', result.responseText); 
                    } 
                });                

        }catch(e){
            this.markInvalid();
        }
        
    }
});
----------------------------------------------------------

Thanks in advance