Programmatically remove Firefox's license agreement dialog

I am running regression tests with Selenium and am automatically launching instances of Firefox.

The problem is my tests get stuck because of Firefox's license agreement dialog:

I can't click with the mouse because I am in an headless environment with a virtual graphical environment.

I would like to know what Firefox's file can I edit (and how to edit it) to trick Firefox into thinking somebody accepted the copyright.

Clarification following comments

I need to do it just once. But I can't do it with the mouse as this is a virtual graphic environment and I don't have mouse or see the mouse pointer. I can however take screenshots.

Solution

OK, I found it by myself in the end.

The right answer is:

In the Firefox installation, look for firefox.js

Find this line:

pref("browser.EULA.3.accepted", false);

and replace false whit true

Thanks to all that helped.