title: ExtJS 4.1.3 filter combobox
body: <p>This is a 2-part question:</p>
  
  <p>Primary Question: Say I have a combobox (code below) that is pulling from a store. Say I have an array that I want to filter the data by so that only certain values actually show up in the dropdown. I can't seem to find the parameter that will do that... Is there a simple way to do this?</p>
  
  <p>Secondary question: I also need to be able to disable and reenable items within the drop down based on actions of the user after the dropdown is created. Is there a function that causes items to be reenabled/disabled within the dropdown?</p>
  
  <p>Note: By disabled I mean 'not present' aka removed in the dom, but still present in the non-filtered store.</p>
  
  <pre><code>{
    xtype: 'combobox',
    anchor: '100%',
    name: 'Permission_id',
    fieldLabel: 'Permissions',
    hideLabel: false,
    displayField: 'Name',
    forceSelection: true,
    store: 'PermissionStore',
    typeAhead: true,
    valueField: 'id',
    valueNotFoundText: 'Add Permission'
  }
  </code></pre>