Listing more applications in exo-preferred-applications

[Sergio]

You would have to report a bug for exo.
But maybe the devs are working on another way to make the default apps work as this way would require desktop files for dozens of apps. Google Chrome, while on its part doing probably quite right on trying to set itself as a default app in Xfce, used to have issues because of Xfce having a chromium.desktop instead.