resizable.py

import pygame, sys
 
mainClock = pygame.time.Clock()
from pygame.locals import *
pygame.init()
pygame.display.set_caption('game base')
monitor_size = [pygame.display.Info().current_w, pygame.display.Info().current_h]
screen = pygame.display.set_mode((500, 500), pygame.RESIZABLE)
 
fullscreen = False
 
while True:
 
    screen.fill((0, 0, 50))
 
    pygame.draw.rect(screen, (255, 0, 0), pygame.Rect(screen.get_width() - 5 - (screen.get_width() / 5), 50, screen.get_width() / 5, 50))
 
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
            sys.exit()
        if event.type == VIDEORESIZE:
            if not fullscreen:
                screen = pygame.display.set_mode((event.w, event.h), pygame.RESIZABLE)
        if event.type == KEYDOWN:
            if event.key == K_ESCAPE:
                pygame.quit()
                sys.exit()
            if event.key == K_f:
                fullscreen = not fullscreen
                if fullscreen:
                    screen = pygame.display.set_mode(monitor_size, pygame.FULLSCREEN)
                else:
                    screen = pygame.display.set_mode((screen.get_width(), screen.get_height()), pygame.RESIZABLE)
 
    pygame.display.update()
    mainClock.tick(60)