This seems to suggest both options are available, at least in a previous version of Gnome 3.

http://unix.stackexchange.com/questions/17660/default-applications-gnome-3

As to why its changed, I assume the RPM upgrade script for Disk Analyser did this. It probably shouldn't.

When I upgrade to Gnome 13 this evening I'll see if I can reproduce this issue.

Sent from my HTC

----- Reply message -----
From: "Ankur Sinha" <sanjay.ankur@gmail.com>
To: "Discussions about development for the Fedora desktop" <desktop@lists.fedoraproject.org>
Subject: Default application handling external USB devices changed to "Disk analyser"?
Date: Thu, Jul 3, 2014 08:32

Hi,

Has the default application that handles USB pluggable devices been
changed to "Disk analyser"? It used to be nautilus iirc. When I used to
plug my devices in, I used to generally get a "Open with Files"
notification. Now I get "Open with Disk Analyser." I'm not sure why I'd
like to open my device with "Disk Analyser" by default - I'd like to use
the device, not see its properties, most of the time. 

Another thing - is it possible to choose an application from the
notification, or can one just use the application that is being
suggested? 
-- 
Thanks,
Warm regards,
Ankur (FranciscoD)

http://fedoraproject.org/wiki/User:Ankursinha

Join Fedora! Come talk to us!
http://fedoraproject.org/wiki/Fedora_Join_SIG