When typing a password for the standard Twitter web interface, the browser is responsive to keystrokes for the Username/email field, but not responsive in the Password field (i.e., it is not possible to log onto Twitter via ArcticFox at this time); this occurs even when all add-ons are disabled
Thanks. I've noticed this as well on a couple sites. In the meantime, if you aren't familiar with these, give them a try for a workaround. https://forums.macrumors.com/threads/facebook-and-twitter-apps-for-tiger-leopard.2104852/
Cheers