⋅ list position is too close to panel, and too low,
⋅ there is no arrow between icon and list ( I should have changed background to emphasize, sorry ),
⋅ mime icon type might be nice in the list,
⋅ icon in panel has a translucent circle background, as no other applet has.
This is an inconsistency with the Gtk toolkit - GTK Menu’s (recently used) look different from GTK PopOvers (places/trash).
GTK Menus was used because they are very easy to program with. PopOvers are a real pain in the a**.
Its would be an interesting project for someone to contribute to - but no plans by the team.