The problem#
Previously, I showed how to get Firefox to show just the web content without any of the window borders or toolbars. But there's an obvious problem: those UI elements are actually useful for doing things with the browser. We can give a single URL as an argument when we start the browser, and that may be good enough for some use-cases, but what if we want to have more control over what the browser is displaying?
The solution#
Firefox has a feature for running automated tests called Marionette which we can use for automating Firefox outside of the context of running tests. There's an official Python client:
$ pip install marionette_driver
$ firefox --marionette &
$ python
>>> from marionette_driver.marionette import Marionette
>>> client = Marionette('localhost', port=2828)
>>> client.start_session()
{'browserName': 'firefox', ... }
>>> client.navigate('https://example.com/')
If it works, you should see Firefox load
the URL https://example.com/.
You can find more information on the available commands on the basics page and the documentation.