title: How to remove event listeners while destroying CKEditor
body: <p>I have a ckeditor plugin like this:</p>
  
  <pre><code>CKEDITOR.plugins.add('testplugin', {
          init: function (editor) {
                 editor.on('contentDom', function (e) {                
                      var body = editor.document.getBody();           
                      body.on('mouseup', function (e) {
                         alert('run!!!!');
                       });
                    });
          });
  });
  </code></pre>
  
  <p>It work perfect in CKEDITOR version 3 (iframe base)</p>
  
  <p>But when i upgrade to CKEDITOR version 4 (lastest - contenteditable base),</p>
  
  <p>all event fire multiple times when i destroy then re-init ckeditor.</p>
  
  <p>(using <code>CKEDITOR.instants.testEditor.destroy()</code> and <code>CKEDITOR.replace('testEditor',options);</code>)</p>
  
  <p>i use: <code>removeAllListeners( )</code> to remove all event listeners to body but no change.</p>
  
  <p>How can i complete destroy CKEDITOR 4 + All event listeners on it?</p>