title: ExtJS - After clearing filter(s) of store, type query does not work
body: <p>I'm using instances of a <code>combobox</code> for multiple user interfaces. So I need to reset combobox stores when user focuses on it. Combo's store is <strong>locally sorted</strong>; so I execute <code>clearFilter()</code> function of <code>Ext.data.Store</code> class - it works as it is expected except that <strong>typing query</strong> does not work anymore.</p>
  
  <p>Here is my <strong>combobox</strong> configuration:</p>
  
  <pre><code>forceSelection: true,
  autoSelect: false,
  typeAhead: false,
  triggerAction: 'all'
  </code></pre>
  
  <p><strong>Store</strong> configuration:</p>
  
  <pre><code>autoLoad: false,
  autoSync: false,
  remoteSort: false,
  proxy: {
      type: 'ajax'
      // other configs
  }
  </code></pre>
  
  <p><strong>Edit:</strong> <a href="https://fiddle.sencha.com/#fiddle/te2" rel="nofollow">fiddle</a></p>
  
  <p><strong>Note:</strong> <code>Store</code> of <code>combobox</code> used in fiddle is populated with <strong>static data</strong> when the original one uses an <code>AJAX proxy</code></p>