title: NullPointerException in PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage()
body: <pre><code> //obtain the active page
   IWorkbenchPage page = PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage();
  </code></pre>
  
  <p>returns Exception in thread "Thread-3" java.lang.NullPointerExceptionµ.
  What shall i do?</p>