"Open containing folder" in Firefox does not use my default file manager

Solution 1:

After a lot of tries, I came upon the very simple method given above by Gill Bates, which was to

1. Go into System Settings
2. Switch default manager to something else
3. Switch it back

So I did that, then closed and reopened Firefox and sure enough, it worked like a charm. Maybe I can invoke Occam's Razor here...

Solution 2:

The suggestion by @carnendil is not wise because the system generates this list at startup and it therefore should not be directly edited by the user. In fact, each entry is supposed to contain all the options available on the system and sometimes the first entry is not the preferred one.

In theory, the suggestion by @Fab should work, but it turns out that sometimes programs attempt to reference defaults.list exclusively. For example, the discussion on Bugzilla reveals that Firefox doesn't even know to look for either of the user's local lists, defaults.list and mimeapps.list.

Therefore, I suggest you edit one of the following files, with the first option probably being the wisest choice unless you are on a multiuser system:

1. Edit /usr/share/applications/defaults.list; or
2. Edit both ~/.local/share/applications/mimeapps.list and ~/.local/share/applications/defaults.list; or
3. Edit one of the files within ~/.local/share/applications/ and then create a symbolic link to that file from the other (e.g. edit ~/.local/share/applications/mimeapps.list and link to it from ~/.local/share/applications/defaults.list).

To one of the following options above, add (or change) the following line:

inode/directory=Thunar-folder-handler.desktop