Then maybe I'm missing something. I've set here: extensions.allow-non-mpc-extensions to true as per https://wiki.mozilla.org/Add-ons/ShimsNightly https://wiki.

Then maybe I'm missing something. I've set here: extensions.allow-non-mpc-extensions to true as per https://wiki.mozilla.org/Add-ons/ShimsNightly https://wiki.mozilla.org/Add-ons/ShimsNightly But when I go to https://addons.mozilla.org/en-US/firefox/addon/vimperator/ https://addons.mozilla.org/en-US/firefox/addon/vimperator/, It wont let me install and it says "This add-on is not compatible with your version of Firefox" Edit: Disabling JS allowed me to download it. It's not working yet, but I haven't had time to troubleshoot.