code: public Widget put(IWidgetFactory factory, int index) throws IndexOutOfBoundsException {
  		Widget widget = factory.getWidget();
  		put(widget, index);
  		return widget;
  	}
docs: Creates new widget and puts it to container
  
  @param factory Factory of new widget
  @param index   index id of 'cell' in the container to put widget to(numbered from 0)
  @return Instance of created widget
  @throws IndexOutOfBoundsException when specified index is negative or there is no more space