Comment 37 for bug 1551171

Bug 568218 points out the correct files to use for this: mimeapps.list → defaults.list, as defined by the mime actions spec https://specifications.freedesktop.org/mime-apps-spec/latest/

The “Default Applications” section says: https://specifications.freedesktop.org/mime-apps-spec/latest/ar01s03.html

> Indicating the default application for a given mimetype is done by writing into the group [Default Applications] in the file mimeapps.list.
> […]
> This example ensures that the application default1.desktop will be used for mimetype1, if it's installed, and otherwise default2.desktop if it's installed:
>
> [Default Applications]
> mimetype1=default1.desktop;default2.desktop