Icedove and mime-types

I'm feeling really stupid. I have an installation of Trinity on Squeeze where the user uses Icedove for email. For some reason, it wants to open PDF files in GIMP. I see the same thing in other Gnome applications like Evolution. I've gone to Icedove preferences and tried to change the application type and clicking on other . . . does not produce a dialog box to select an application (like KPDF or acroread). I installed kgtk-config-icedove but that did not help. I even installed Nautilus and tried setting the application association there. That at least presented KPDF as an option in Evolution but not in Icedove. I installed gconf-editor but that does not seem to address application associations. Short of finding which defaults.list file it is looking at and manually editing it or manually setting it in mimetypes.rdf, how does one set this in a Trinity only environment (in that Gnome desktop is not installed)? Thanks - John