public function setPosition( $horizontal, $vertical )
	{
		if( in_array( $horizontal, array( 'left', 'center', 'right' ) ) )
			$this->positionH	= $horizontal;
		else
			throw new InvalidArgumentException( 'Horizontal Position "'.$horizontal.'" must be on of (left, center, right).' );
		if( in_array( $vertical, array( 'top', 'middle', 'bottom' ) ) )
			$this->positionV	= $vertical;
		else
			throw new InvalidArgumentException( 'Vertical Position "'.$horizontal.'" must be on of (top, middle, bottom).' );
	}