How to set system-wide default application for protocol handler?
I've got a multi-user system.
When a user clicks a link "hello:world" or similar in firefox, an external application shall open the link.
I created /usr/share/applications/hello.desktop:
Now, when a user clicks a link, he gets a window shown "This link needs to be opened with an application. Send to: [Choose an Application]".
However, the user should not need to choose anything. I want him to just click the hello: link and the application shall run without any further action.
How can I setup such a system default?
Running either Debian with gnome3 or Ubuntu with unity.