Add support for further desktop standards, for example the default application to open a file type (https://specifications.freedesktop.org/mime-apps-spec/latest/ar01s04.html).

Generate a file open association per application instead of per extension, so each application appears in Freedesktop's right-click list and "Open with" list only once. I already sent patches for this long ago, but I don't think people understood them:

Damjan