code: public void removeListener(IProblemChangedListener listener) {
  		fListeners.remove(listener);
  		if (fListeners.isEmpty()) {
  			VdmUIPlugin.getWorkspace().removeResourceChangeListener(this);
  //			JavaPlugin.getDefault().getCompilationUnitDocumentProvider().removeGlobalAnnotationModelListener(this);
  		}
  	}
docs: Removes a <code>IProblemChangedListener</code>.
  @param listener the listener to remove