title: listener for cell selection extjs grid
body: <p>I have a grid which contains just one column. Each row essentially contains just a name. When I click on a particular name I populate a form on the right side of the column using that selected name. </p>
  
  <p>Now what I wish to do is whenever a user selects ANOTHER name, whatever changes he has made in the components on the form on the right side for the last selected name, I wish to save them. All I need is a method to be able to just launch this saving function whenever he moves on to the next name. </p>
  
  <p>The tricky thing is that the save should be done BEFORE I populate the components on the right side for this new selection. For populating I am using a <code>selectionchange</code> listener. </p>
  
  <p>So in essence I want to be able to know my previous selection name and to be able to launch a save function and then populate the form with the current selection name.</p>
  
  <p>Here's a flow for clarity:</p>
  
  <pre><code>let user select one name -&gt; 
  let user make changes on the form on right side -&gt; 
  let user select new name -&gt; 
  
  // I need help in the next step
  
  launch save function for previously selected name -&gt; 
  populate the right hand side form using new/current selection.
  </code></pre>