title: Extjs superclass.constructor.call usage
body: <p>I'm new to Extjs.</p>
  
  <p>What is the meaning of Extjs superclass.constructor.call ?</p>
  
  <p>I saw it used in Extjs examples <a href="http://dev.sencha.com/extjs/5.0.0/examples/index.html" rel="nofollow">http://dev.sencha.com/extjs/5.0.0/examples/index.html</a></p>