title: Can't open more than max number of tabs with Selenium Webdriver?
body: <p>I am trying to open a list of different URLs, opening one per tab, but when the number exceeds 20 ~ 21, stop opening tabs.</p>
  
  <p>I've tried to separate the list into groups of 20, and creating new instances of the webdriver, and that works fine, but I would like to know if it's a way to enable more number of tabs using the same instance? </p>
  
  <pre class="lang-python prettyprint-override"><code>from selenium import webdriver
  import time
  
  driver = webdriver.Firefox()
  driver.get('https://stackoverflow.com/')
  
  for i in range(30):
      driver.execute_script("window.open('');")
  
  print(len(driver.window_handles))
  time.sleep(3)
  driver.quit()
  </code></pre>
  
  <p>I was trying, to open 30 tabs at once but only opens 21.
  I'm using python 3.5.0, Firefox 68.0.2 &amp; geckodriver 0.24.0</p>