code: protected function getSpacesByCore($up = false)
  	{
  		$free = $this->getTotalWidth() - $this->getBordersLength() - $this->getCoreLength();
  
  		return $free < 1 ? '' : str_repeat(' ', $this->roundHalf($free, $up));
  	}
docs: Retrieve the blank spaces close to the core.
  
  @author	Andrea Marco Sartori
  @param	boolean	$up
  @return	string