Updating PagingToolbar on ExtJs Filter (Version 3)

gistfile1.js

var store = new Ext.data.JsonStore({root: "data", url: "<url>", totalProperty: 'totalCount', idProperty: 'id',method: 'POST', fields:[]});
var page = new Ext.PagingToolbar({pageSize: 25, store: store});
var grid = new Ext.grid.GridPanel({store: store, tbar: page});

store.load({params:{start:0, limit:25}});
grid.render('#exapmle');

grid.on('filterupdate', function(){
    var o = {}, pn = this.store.paramNames;
    o[pn.start] = 0;
    o[pn.limit] = page.pageSize;
    this.store.load({params:o});
});