How can I get Firefox to use Dolphin instead of Nautilus?

sudo apt-get install kmozillahelper

is not more available.

How to use dolphin to open folder in firefox

When I installed KDE and Firefox this feature actually worked – I downloaded a file, clicked on “open containing folder”, and Dolphin would happily pop with the respective folder open.

However, when I installed a few more apps, Firefox started calling Gwent or other app to “open the folder”.

Solution:

In the file /usr/share/applications/mimeinfo.cache, find inode/directory and make kde4-dolphin.desktop on first such as:

inode/directory=kde4-dolphin.desktop;kde4-gwenview.desktop;kde4-kfmclient_dir.desktop;

As user162413 stated, kmozillahelper is no longer avaliable. His solution however did not work for me.

Instead, one from dragly did the trick:

Open up /usr/share/applications/defaults.list and change line

inode/directory=nautilus.desktop

to

inode/directory=kde4/dolphin.desktop

Works without need to restart Firefox.

To get Dolphin in the file-picker dialog, install the package "kmozillahelper" from the standard repositories.

sudo apt-get install kmozillahelper

Set the filepicker-variable in in Firefox by visiting the URL about:config.

More information here