title: error in a spray project
body: <p>I am a masters student, and as I am preparing my final project study which requires to have a graphical editor for a DSL named <code>"VERISENSOR"</code>, I need to work with <code>"SPRAY"</code>. 
  while following the tutorial that I found on eclipse, I found a problem in the file ( .spray )
  once I add a class in this file, the following errors are displayed: </p>
  
  <pre><code>org.eclipse.emf.ecore.impl.DynamicEObjectImpl cannot be cast 
  to org.eclipselabs.spray.mm.spray.ShapeInSpray 
  org.eclipse.emf.ecore.impl.DynamicEObjectImpl 
  </code></pre>