Increments the document font size.

        :param value: Font size increment.
        :type value: int
        :return: Method success.
        :rtype: bool

def set_font_increment(self, value):
        """
        Increments the document font size.

        :param value: Font size increment.
        :type value: int
        :return: Method success.
        :rtype: bool
        """

        font = self.font()
        point_size = font.pointSize() + value
        if point_size < self.__minimum_font_point_size or point_size > self.__maximum_font_point_size:
            return False

        font.setPointSize(point_size)
        self.setFont(font)
        return True