Comment 92 for bug 18995

the use-case of opening a file could be:
(default -but rules could be specified by user to overpass the default association)
automatically use the preferred user's application using xdg-open.
IF NO preferred association found
THEN popup dialog to the user like this http://www.amsn-project.net/w/upload/a/ab/Screenshot-4-5.jpg
giving him the choice between manual path or a list of available application (using freedesktop standard specification)
..my two cents..