[Shotwell] External Editor

[Chris Game]

How can I set my preferred external editor? There is no 'Browse'
button as there is for the import folder. The only choice I have is
to use the 'Image Viewer' (which happens to be Eye of Gnome on here)
in the dropdown list - it is the only item in the list. I would like
to use a particular editor I have installed - which happens to be
running under wine. Although that editor appears on the Applications
menu it is not found by Shotwell. Is there a config file that can be
directly edited to point to my preferred application (I can't see
one)?

Installing GIMP just to get this feature seems a little over the
top!

Shotwell 0.6.0 on Debian Squeeze/Gnome.