UIProgressBar in Pygame_GUI. Filling the scale of progress bar

Question

I'm trying to figure out how to make the progress bar fill the scale not from 100% maximum, but from the maximum value I set. Because even after the definition maximum_progress on 10, and current_progress in 10, scale filling on 10%, not 100%, as I want.

import pygame
import pygame_gui as pg

pygame.init()

window_surface = pygame.display.set_mode((800, 600))
background = pygame.Surface((800, 600))
background.fill(pygame.Color('#000000'))
manager = pg.UIManager((800, 600))

pg.elements.ui_button.UIButton(pygame.Rect((300, 100), (200, 50)), manager=manager, text='+1')


class MyProgressBar(pg.elements.UIProgressBar):
    def __init__(self, x, y, w, h, ui_manager):
        super().__init__(relative_rect=pygame.Rect((x, y), (w, h)), manager=ui_manager)
        self.current_progress = 0
        self.maximum_progress = 10

    def status_text(self):
        return f"{self.current_progress:0.1f}/{self.maximum_progress:0.1f}"

    def set_current_progress(self, progress):
        self.current_progress = progress
        self.percent_full = progress


prog = 0
progressbar = MyProgressBar(300, 200, 200, 50, manager)

is_running = True
clock = pygame.time.Clock()

while is_running:
    time_delta = clock.tick(60) / 1000.0

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            is_running = False
        if event.type == pg.UI_BUTTON_PRESSED:
            prog += 1

        manager.process_events(event)

    progressbar.set_current_progress(prog)
    progressbar.redraw()
    manager.update(time_delta)

    window_surface.blit(background, (0, 0))
    manager.draw_ui(window_surface)

    pygame.display.update()

Perhaps there is some method or variable that is not mentioned in the documentation. Or mentioned in the description of another element, as it was with UIDropDownMenu and parametr "list_item_height". I will be grateful for any hint.