title: Checkbox selection model - radio button styling?
body: <p>I'm using ExtJs 4 to build out a new web page with a few forms in it, nothing crazy. On this page I have a gridpanel using a checkbox selection model with mode set to 'Single'. Here is my selection model configuration:</p>
  
  <pre><code>Ext.create('Ext.selection.CheckboxModel', {
      mode: 'Single',
      checkOnly: true,
      showHeaderCheckbox: false
      /*listeners: {
          select: function(model, record, idx) {},
          deselect: function(model, record, idx) {}
      }*/
  });
  </code></pre>
  
  <p>Functionally speaking, this works absolutely fine. It limits the user to one selection in the gridpanel in which is it being used. However, in my requirements this field is defined as a radio button (which makes sense since in basic HTML this would be the input type used for a single selection, not a checkbox).</p>
  
  <p>Is there configuration setting I could add to the selection model to make the field display as radio buttons instead of checkboxes? Alternatively, is there a CSS update I could make to show the field as a radio button?</p>