Here is the a sample code to maximise firefox window in python.
from selenium import webdriver
driver = webdriver.Firefox()
print driver.get_window_size()
driver.set_window_size(480, 320)
print driver.get_window_size()
driver.maximize_window()
print driver.get_window_size()
Also, there is an another way by setting position, If above code won't work for you then, try the code below:
driver.manage().window().setPosition(new Point(-2000, 0));