title: Extjs defining custom field with getValue and setValue
body: <p>I have defined a custom form field in ext js.<br>
  The custom field just contain a button (this button can be event some text or image, whatever).<br>
  I want to force my value. so I set the <code>getValue</code> to return some string.<br>
  The method is not invoked.<br>
  I want 2 things to happened.<br>
  1. <code>getValue</code> will be the value that will be sent in the submit.<br>
  2. <code>setValue</code> will give me the data that <code>form.load(...)</code> has loaded, and I will handle it my way...</p>
  
  <p>here is an example, click on the submit and you'll see that <code>getValue</code> is not bee called. <a href="http://jsfiddle.net/RB9Hp/" rel="nofollow">http://jsfiddle.net/RB9Hp/</a>  </p>
  
  <p>or this more real life use-case : <a href="http://jsfiddle.net/FTV3R/" rel="nofollow">http://jsfiddle.net/FTV3R/</a> &lt;- this will not send the value from getValue</p>
  
  <pre><code>Ext.define('Ext.form.CustomField', {
      extend: 'Ext.form.FieldContainer',
      alias: 'widget.customfield',
  
      width: 300,
      constructor: function(config) {
          this.callParent([config]);
      },
      getValue : function(){
          console.log("getValue");
          return "test"; // I want to force new value.
      },
      setValue : function(val){},
      initComponent: function() {
          this.items = ([{'xtype' : 'button',text : 'some button'}]);
          this.callParent();
      }
  });
  </code></pre>