title: How to control connection after deletion of node?
body: <p>Here is the example of Undo/Redo : <a href="http://draw2d.org/graphiti/jsdoc/#!/example/buildin_commandstack" rel="nofollow">Undo_Redo_Delete</a></p>
  
  <p>I did the following steps :</p>
  
  <ol>
  <li>Drag and Drop start and end nodes.</li>
  <li>Connect them via ports.</li>
  <li>Delete end node.</li>
  <li>Now again drag end node.</li>
  <li>This time I again try to connect start and end node , but it shows </li>
  </ol>
  
  <p>TypeError: this.parent.getCanvas() is null</p>
  
  <p>at this.parent.getCanvas().connectionLine.setGlow(false) of port.js.</p>
  
  <p>If any body know how to overcome this problem then please help me.Thanks in advance:)</p>