Great extension, Makes browsing on Firefox Android much smoother.
It would be nice if the virtual button auto-hid when entering full-screen, and we could exit using the native Android back gesture or system controls.
Being able to change the icon would be a cool bonus. I like the current one, but having options is always welcome.
Also, allowing users to reposition the button on the screen (corners, center, etc.) would help with ergonomics, especially on larger phones.
Awesome work! really functional.