[Shotwell] Choosing application opened by "Show in file manager"

[Joseph Bylund]

I'm having an issue where when I right click a photo in my library and 
select "Show in file manager" eog (previously "eye of gnome" now "gnome 
image viewer" is opened).  How do I select which application is opened 
by this action (I would prefer thunar). I want to check that there is 
not something that I'm missing before I open a ticket.
-Joe