Selenium: window doesn't open after click

I am using selenium 3.4.3 and python 3.6.2 and I have a problem where I want to open a new window. First of all, this is the part of the code where it fails:

def wait_and_find_by_id(element_id):
    WebDriverWait(driver, 10).until(
        EC.presence_of_element_located((By.ID, element_id))
    )
    return driver.find_element_by_id(element_id)

VA = wait_and_find_by_id('VA_id')
driver.execute_script("window.showModalDialog = window.open;")
VA.click()

# Wait for the new window to open
time.sleep(2)
driver.switch_to_window(driver.window_handles[2])

tarifaire = driver.find_element_by_xpath("//*[@id='tarif_id']/span/span")
driver.execute_script("window.showModalDialog = window.open;")
tarifaire.click()

      

        
        
        
      

    

I have no problem opening a window for the first time ( VA.click()

), but when I try to open a second window ( tarifaire.click()

), the window seems to be refreshed and nothing else happens.

I tried to run the script without a second instance driver.execute_script

and the window opens but as a popup and my program gets stuck until I close the popup.

I can give you more information if you need it to help me.

Update. It turns out this works well with ChromeDriver, I don't even need to use driver.execute_script

. But still, if anyone knows why the above script doesn't work with Firefox Geckodriver, I'd love to hear it!