Paginação com EXT JS e JSON

/
Ext.onReady(function(){

    // create the Data Store
    //pega dados via JSON
    var store = new Ext.data.JsonStore({
        //lista
        root: 'users', 
        //total de registros
        totalProperty: 20,
        //id da lista
        idProperty: 'id',
        remoteSort: true,

        fields: [
            'id', 'name','login'
        ],

        // load using script tags for cross domain, if the data in on the same domain as
        // this page, an HttpProxy would be better
        proxy: new Ext.data.ScriptTagProxy({
            //url: 'http://extjs.com/forum/topics-browse-remote.php'
            url: 'http://localhost:8080/dvd/user.list.ajax.logic'
        })
    });
    //campo para ordenação default
    store.setDefaultSort('login', 'desc');



    var pagingBar = new Ext.PagingToolbar({
        pageSize: 10,
        store: store,
        displayInfo: true,
        displayMsg: 'Exibindo Usuários {0} - {1} of {2}',
        emptyMsg: "Não existe usuários cadastrados",
        
        items:[
            '-', {
            pressed: true,
            enableToggle:true,
            text: 'Show Preview',
            cls: 'x-btn-text-icon details',
            toggleHandler: function(btn, pressed){
                var view = grid.getView();
                view.showPreview = pressed;
                view.refresh();
            }
        }]
    });

    var grid = new Ext.grid.GridPanel({
        el:'topic-grid',
        width:700,
        height:300,
        title:'Exemplo Paginação Grid',
        store: store,
        trackMouseOver:false,
        disableSelection:true,
        loadMask: true,

        // grid columns
        columns:[{
            //id: 'topic', // id assigned so we can apply custom css (e.g. .x-grid-col-topic b { color:#333 })
            header: "ID",
            dataIndex: 'id',
            width: 200,
            //renderer: renderTopic,
            sortable: true
        },{
            header: "Name",
            dataIndex: 'name',
            width: 200,
            align: 'right',
            sortable: true
        },{
            //id: 'last',
            header: "Login",
            dataIndex: 'login',
            width: 300,
            //renderer: renderLast,
            sortable: true
        }]

        // paging bar on the bottom
        bbar: pagingBar
    });

    // render it
    grid.render();

    // trigger the data store load
    store.load({params:{start:0, limit:25}});
});



/**
 * @class Ext.ux.SliderTip
 * @extends Ext.Tip
 * Simple plugin for using an Ext.Tip with a slider to show the slider value
 */
Ext.ux.SliderTip = Ext.extend(Ext.Tip, {
    minWidth: 10,
    offsets : [0, -10],
    init : function(slider){
        slider.on('dragstart', this.onSlide, this);
        slider.on('drag', this.onSlide, this);
        slider.on('dragend', this.hide, this);
        slider.on('destroy', this.destroy, this);
    },

    onSlide : function(slider){
        this.show();
        this.body.update(this.getText(slider));
        this.doAutoWidth();
        this.el.alignTo(slider.thumb, 'b-t?', this.offsets);
    },

    getText : function(slider){
        return slider.getValue();
    }
});

{"users":[
 	{
 	"dvds":null,
 	"id":1,
 	"login":"fabio.pedrosa",
 	"name":"Fabio Pedrosa",
 	"password":null
 	},
	{
	"dvds":null,
	"id":2,
	"login":"teste",
	"name":"Teste",
	"password":null
	}
	]
}

{"totalCount":"47865",
	"topics":[
	{
	       "threadid":"58073",
	       "forumid":"9",
	       "forumtitle":"Ext: Help",
	       "title":"Can I use one store and filter it differently for two different views?",
	       "author":"tapani108",
	       "lastposter":"Condor",
	       "lastpost":"[telefone removido]",
	       "excerpt":"Hello, \n\nI am attempting to create one JSON store, simplified below:\n\nvar downloadQueueAllItems= new Ext.data.JsonStore({\n\n root: 'downloadQueue',\n fields: ['DownloadId', 'ElementId', 'CurMainStatus'],\n data: { downloadQueue: [\n{ \"DownloadId\": 1,\n \"ElementId\": 113...",
	       "replycount":"4"
       },
       ]
}

"totalCount":"47865"

var store = new Ext.data.JsonStore({
        //lista
        root: 'users', 
        //total de registros
        totalProperty: 20,
        //id da lista
        idProperty: 'id',
        remoteSort: true,

columns:[{
            //id: 'topic', // id assigned so we can apply custom css (e.g. .x-grid-col-topic b { color:#333 })
            header: "ID",
            dataIndex: 'id',
            width: 200,
            //renderer: renderTopic,
            sortable: true
        },{
            header: "Name",
            dataIndex: 'name',
            width: 200,
            align: 'right',
            sortable: true
        },{
            //id: 'last',
            header: "Login",
            dataIndex: 'login',
            width: 300,
            //renderer: renderLast,
            sortable: true
        }],