Seems like it should've been asked before, but couldn't find. It's not this.
I never had to use the alt key on a website before, until now. The website is https://bezier.method.ac which basically is a game to master Photoshop's pen tool. In order to use it, you need to have the alt key working within the website, to click while holding it (to split handles).
However, this fails within my Firefox (Arch Linux). All it does when I press the alt key is bring up the menu bar. The key seems to not be usable for anything else. I'm using an AUR maintained version of the older Firefox (version 56.0.2).
So my simple question is: How can I use the alt key within websites? If that means having to disable the alt-key-brings-menubar-up thing: I would be totally fine with that.
Update (in case this helps): When I set the
mousewheel.with_alt.action property within
2, the behavior of alt+scroll becomes navigate history as expected. So the key itself and Firefox' shortcuts involving it are definitely working fine.