module/Customize/src/Grid/Customize/Model/Rule/Structure.php
protected function setBackgroundPositionXProperty( $value, $priority = self::PRIORITY_NORMAL )
    {
        $x = (string) $value;
        $y = (string) $this->getRawPropertyValue( 'background-position-y' );

        if ( '' !== $x && '' !== $y )
        {
            $this->setRawProperty(
                'background-position',
                $x . ' ' . $y,
                $priority ?: $this->getRawPropertyPriority(
                    'background-position-y'
                )
            );
        }

        return $this->setRawProperty( 'background-position-x', $x, $priority );
    }
protected function setBackgroundPositionXProperty( $value, $priority = self::PRIORITY_NORMAL )
    {
        $x = (string) $value;
        $y = (string) $this->getRawPropertyValue( 'background-position-y' );

        if ( '' !== $x && '' !== $y )
        {
            $this->setRawProperty(
                'background-position',
                $x . ' ' . $y,
                $priority ?: $this->getRawPropertyPriority(
                    'background-position-y'
                )
            );
        }

        return $this->setRawProperty( 'background-position-x', $x, $priority );
    }
protected function setBackgroundPositionXProperty ( $ value , $ priority = self :: PRIORITY_NORMAL ) { $ x = ( string ) $ value ; $ y = ( string ) $ this -> getRawPropertyValue ( 'background-position-y' ) ; if ( '' !== $ x && '' !== $ y ) { $ this -> setRawProperty ( 'background-position' , $ x . ' ' . $ y , $ priority ? : $ this -> getRawPropertyPriority ( 'background-position-y' ) ) ; } return $ this -> setRawProperty ( 'background-position-x' , $ x , $ priority ) ; }
Set background-position-x

@param string $value
@param string $priority
@return \Customize\Model\Rule\Structure
Set background - position - x