code: protected Button newButton(final String id)
  	{
  		return new AjaxButton(id)
  		{
  			/**
  			 * The serialVersionUID.
  			 */
  			private static final long serialVersionUID = 1L;
  
  			/**
  			 * Listener method invoked on form submit with errors
  			 *
  			 * @param target
  			 * @param form
  			 */
  			@Override
  			protected void onError(final AjaxRequestTarget target, final Form<?> form)
  			{
  				SigninFormPanel.this.onSignin(target, SigninFormPanel.this.form);
  			}
  
  
  			/**
  			 * {@inheritDoc}
  			 */
  			@Override
  			public void onSubmit(final AjaxRequestTarget target, final Form<?> form)
  			{
  				SigninFormPanel.this.onSignin(target, SigninFormPanel.this.form);
  			}
  		};
  	}
docs: Factory method for creating the new {@link Button}. This method is invoked in the constructor
  from the derived classes and can be overridden so users can provide their own version of a
  new {@link Button}.
  
  @param id
  the id
  @return the new {@link Button}