Fedora 23 : Firefox : Auto Full Screen

To start Firefox in full screen mode, install r-kiosk extension

https://addons.mozilla.org/en-US/firefox/addon/r-kiosk/

Close your Firefox, then, every time you load your Firefox, it will be in full screen mode.

This is how my screen looks when I load Firefox:

Nice! Now i want to disable it to be able to access Firefox' other functions...

To disable full screen, start Firefox in safe mode by launching through terminal:

# firefox -safe-mode

Then go to the burger icon (Menu) > Add-ons > Extensions > Disable R-kiosk

Done.