Hey there! The Q is a hotkey that works when the right click options is pressed. Strictly personal hunch until I'll dig through some version update when Q hotkey function was added, I believe we'll probably read in said version update report that it serves as part of the overall Ease of Access. Be it hardware peripherals malfunctioning, or fellow Mozillians with some health or imparities, but the short solution for solving your curiosity, additionally how to make use of it, as mentioned above. Just a right click, and then press Q. Sometimes hardware malfunctions like the touchpad of a laptop might not work and the user is unable to promptly purchase a mouse, as such, most keyboards have the right click key, and Q. Now how does one navigate inspect element without a mouse is an entire conundrum even I'd like to know, I'd imagine with a liberal use of tapping tab key until reaching the desired category, but that's just a theory. A Mozzillian theory! :D