The source code

###

    Ext.onReady(function(){

        var ds = new Ext.data.Store({
            proxy: new Ext.data.ScriptTagProxy({
                url: 'http://extjs.com/forum/topics-remote.php'
            }),
            reader: new Ext.data.JsonReader({
                root: 'topics',
                totalProperty: 'totalCount',
                id: 'post_id'
            }, [
                {name: 'title', mapping: 'topic_title'},
                {name: 'topicId', mapping: 'topic_id'},
                {name: 'author', mapping: 'author'},
                {name: 'lastPost', mapping: 'post_time', type: 'date', dateFormat: 'timestamp'},
                {name: 'excerpt', mapping: 'post_text'}
            ])
        });

        // Custom rendering Template
        var resultTpl = new Ext.XTemplate(
            '',
                '{lastPost:date("M j, Y")}
    by {author}{title}',
                '{excerpt}',
            ''
        );

        var search = new Ext.form.ComboBox({
            store: ds,
            displayField:'title',
            typeAhead: false,
            loadingText: 'Searching...',
            width: 570,
            pageSize:10,
            hideTrigger:true,
            tpl: resultTpl,
            applyTo: 'search',
            itemSelector: 'div.search-item',
            onSelect: function(record){ // override default onSelect to do redirect
                window.location =
                    String.format('http://extjs.com/forum/showthread.php?t={0}&p={1}', record.data.topicId, record.id);
            }
        });
    });