title: Adding listener to Ext.grid.ColumnModel
body: <p>i was trying to add a listener(columnshow) to Ext.grid.ColumnModel inside a Ext.grid.GridPanel, but my listener function is not being called.</p>
  
  <p>pls help.</p>
  
  <p>parts of code pasted below.</p>
  
  <pre><code>    var gridCm = new Ext.grid.ColumnModel({
         columns  : data.result.columns,
         listeners    : {
              columnshow  : function( a , b ) {
                  alert(1);   
              }   
         }
      });
  </code></pre>