Question: I just switched to Fedora 22 and decided to go for Gnome3 this time instead of XFCE. I like the `Thunar` file manager so I downloaded it. I've had trouble setting it as the default file manager though.

**What I tried:**

I ran `exo-preferred-applications`. Under `Utilities -> File Manager` I selected `Thunar`.

**The problem:**

It's not acting as the default file manager. When I open my `Downloads` folder from my browser I still get `Nautilus`. Same when I click on my `"Places"`.

Answer: 
You could try editing `/usr/share/applications/defaults.list` and changing the line

```
inode/directory=nemo.desktop;caja.desktop;nautilus.desktop;Thunar.desktop;kde4-dolphin.desktop

```

to 

```
inode/directory=Thunar.desktop;

```

or some order that suits your needs.
In Fedora 25, the appropriate file is `/usr/share/applications/gnome-mimeapps.list`. Change the `inode/directory` entry to point to your file manager of choice. Change takes place immediately and the Places menu opens the newly selected application.