Ivanblanc, thank you very much for posting a version of the search plugin for 4.0.
When I view my grid, the search box is visible. However, when I enter a search term and hit enter, nothing happens.

I looked at Firebug and discovered that there was an error saying b is undefined. It involves the Extjs-all.js file, line 7, which is here: (function(){var e=this,a=Object.protot...ate("Ext.XTemplate",j,g)}return j}});

I have selected the "local" option in my searching.js file, just to keep things simple for now.

the only other strange thing I've noticed is that searching.js file has a line reading "this.grid = this.view.up('gridpanel');". If I change the gridpanel to fit my grid name, it also creates an error saying that it is undefined.

Any ideas from anyone?

Here is an except from my code:
Ext.define('User', {   extend: 'Ext.data.Model',   fields: ['recordnumber', 'itemprice']});

Ext.define('UsersGrid', {
  extend: 'Ext.grid.Panel',   initComponent: function() {
    var userStore = Ext.create('Ext.data.Store', {
        autoLoad: true,  model: 'User',
        proxy:     {
            type: 'ajax',
             api: {
                read: 'extjs/database.php?task=LISTING',
            reader: { type: 'json', root: 'results',  },
 Ext.apply(this, {  viewConfig:{ forceFit: false, stripeRows: true, trackOver: true  },
      store: userStore,
      features: [searching],
      columns: [{ text: 'Record', width: 45, sortable: true,  hideable: true,  dataIndex: 'recordnumber' },
      { text: 'Item Price', renderer: 'usMoney',  width: 55, sortable: true, hideable: true,
         dataIndex: 'itemprice'}],
 // paging bar on the bottom
        bbar: Ext.create('Ext.PagingToolbar', {
            store: userStore,
            displayInfo: true,
            displayMsg: 'Displaying topics {0} - {1} of {2}',
            emptyMsg: "No topics to display",

Ext.onReady(function() {
   var grid1 = Ext.create('UsersGrid', { renderTo: 'place-for-grid', height: 300, width: 600, title: 'Database' });