Firefly Extension Turns Firefox into a File Browser

“Nowadays, Web browsers can act as front ends to many other
kinds of applications. For instance, if you want to browse and open
the files on your hard drive from within Firefox, turn to the
Firefly extension.

“After you install Firefly, you must configure it before you can
use it. Select Tools -> Addons, scroll down to the extension,
and click on Options. Firefly has six screens’ worth of options.
Under General you can set such things as deciding whether to show
hidden files, open a sidebar from which to browse and select
directories and files by default, and play music