title: How to change data produced by CKEditor dialog
body: <p>I want to do some stuff with the image that is added using Image toolbar button in CKEditor. 
  I actually want to get the url and modify if required. </p>
  
  <p>How can I do it?</p>
  
  <p>I am able to do that stuff using <code>dataFilter</code> but only when image is directly <em>pasted</em> into the
  editor. But <code>dataFilter</code> rule doesn't execute when image is added using default Image button in editor. </p>
  
  <pre><code>CKEDITOR.replace( 'idContent' );
  
  CKEDITOR.on( 'instanceReady', function( e ) {
      CKEDITOR.instances.idContent.dataProcessor.dataFilter.addRules( {
          elements: {
              "img": function (element) {
                  var imageSrcUrl = element.attributes.src;    
                  // Do some stuffs here.     
              }
          }
      } );
  } );
  </code></pre>