title: Single Selection not working in Extjs Grid
body: <p>This is how I set up my selection model for my grid :</p>
  
  <pre><code>var selM = Ext.create('Ext.selection.Model', {
      mode: 'SINGLE',
      toggleOnClick: true,
      allowDeselect:true
  });
  </code></pre>
  
  <p>And then in my table I add this as a configuration paramater :</p>
  
  <pre><code>var packageGrid = Ext.create('js.grid.MyGrid', {
      selModel: selM 
  });
  </code></pre>
  
  <p>The <strong><em>MULTI</em></strong> selection is disabled, which is great. However now <em>nothing</em> remains selected. If I click on a row the highlighting disappears as soon as I move the mouse away.</p>
  
  <p>This could be an extjs bug. I have tried the other parameter 'SIMPLE' as well.</p>
  
  <p>Here is a fiddle which shows my problem :</p>
  
  <p><a href="http://jsfiddle.net/fgkb8yw5/1/" rel="noreferrer">http://jsfiddle.net/fgkb8yw5/1/</a></p>