Set new default file manager for firefox in Archlinux

Currently (2018-09-25) there exists no user-configurable way to change this behaviour in Firefox.

This is a known bug: Firefox does not use default file manager

It was first reported on Bugzilla on 2016-07-08. At the time of writing this bug is unassigned and unresolved.

I'd have a similar problem running Manjaro 4.18.9-1. After install nautilus for a test, firefox started to open folders with nautilus, I removed nautilus and firefox then opened folders with Atom.

At least for me, this solution worked:

• Close firefox
• Go to your file manager (Thunar in my case), right click on a folder and click on "open as"
• Mark "use this app as default" and choose your file manager
• Open firefox and see if it worked